Personal relationships between players and coaches in women's football have been described as "inappropriate", because they create a "power imbalance" and can lead to a "potential abuse of players".
But they still exist at many clubs in the top two leagues in England and several sources have told BBC Sport that everyone in women's football knows of at least one.
So why are they so common and should they be allowed to happen?
It's a taboo subject which contributed to Mark Sampson's sacking as England manager in 2017 and still concerns Women's Super League club board members, coaches and players that BBC Sport has spoken to.
And it's an issue which has been debated again after the recent scandal in America's NWSL, where English coach Paul Riley was sacked from his job at North Carolina Courage following allegations of sexual misconduct with two players, which he denies.
One of those players - Mana Shim, who was coached by Riley at Portland Thorns - said seven of the eight male coaches she worked with had personal relationships with players, and one of four female coaches.
"There's a power imbalance that makes any sexual or romantic relationships inappropriate," she added. "Why is this our norm?"
Similar questions were raised after Sampson lost his job after "inappropriate and unacceptable behaviour" with players in his role at Bristol Academy.
But because player-coach relationships are not illegal, as long as no minors are involved, they are still allowed to happen, albeit they can breach codes of conduct.
It leads to lots of grey areas - not helped by a perceived culture of silence in the game because so many have had first- or second-hand experience of such personal relationships.
That is why there are calls from players, coaches and unions for further education on what is a highly sensitive issue.
"You can't help who you fall in love with" was a phrase used on several occasions in the course of BBC Sport's research - hinting at the acceptance of player-coach relationships in women's football, and how they often don't cause any problems in a team.
It is worth remembering the WSL did not turn professional until 2011 and that football, like many other sports, offers a great opportunity for amateur players to socialise. Same-sex player relationships are also common in the game.
FA director of women's football Sue Campbell declined to be interviewed for this article, but said in 2018 that she regarded player-coach personal relationships as "a concern" - and it is a view shared by many in the game - some of whom have spoken to BBC Sport anonymously.
That anonymity reflects a desire not to expose friends or coaches. There are players and coaches who have had these types of relationships who still play and work at the top of the English game.
Yet several sources have questioned whether they are still appropriate, and claim coaches involved can show an "unconscious bias" when it comes to team selection.
Another source said it was "difficult to control" player-coach relationships in women's football, especially when there was lots of social interaction outside of the team environment.
But there are signs attitudes towards player welfare are shifting, perhaps reflecting the growing professionalism in the game.
Codes of conduct among players and managers are a condition of clubs getting a WSL licence, and every club must have a safeguarding officer in place.
One board member also told BBC Sport they would "seriously consider" whether to appoint anyone who had existing relationship with a player because of the "potential for disruption".
And a number of managers said they "strongly encouraged" staff not to pursue romantic relationships. Others say it should be seen as a "no-go" area, yet it still happens.
Former Everton, Bristol Academy and Leeds defender Alex Culvin now works in player relations at global union Fifpro and has written a PhD on player welfare in women's football.
She told BBC Sport protection for players in England and other countries could be improved.
"You play professional sport from a very young age and you become impressionable," she said. "Power dynamics are very evident and the exploitation of those power dynamics can and do happen.
"A lot of it is about subconscious bias or subtle manipulation of players or power dynamics, and the control and abuse of players.
"In a player-coach relationship, it doesn't necessarily mean that it has to be sexual or even physical. In a lot of cases it can be emotional or actually having the recognition to say: 'I'm not comfortable with that.'
"I'm not in a position to tell anybody who they can and can't fall in love with. But what should be in place are very clear frameworks and guidelines about what constitutes transgression, what constitutes as overstepping the mark. That should be player-led.
"I think, at the moment, there's a lack of clarity on what constitutes 'OK' and that will vary from club to club, from culture to culture, player to player and even association to association. If we can get some commonality across the board, and better understanding that is fundamentally built on education, players will have a better recognition of what is acceptable."
The FA told BBC Sport that "in general, coach and adult player relationships are not advised because of the potential for power imbalance and the impact on team culture and dynamics".
It added: "These are usually matters for clubs to manage via codes of conduct and expected standards of behaviour."
While most players would probably notice serious transgressions, there are still "microaggressions" according to Culvin, hence the call for clearer guidelines and more education. Culvin says this is on FifPro's agenda.
In the aftermath of the NWSL scandal, more allegations of sexual harassment in women's football emerged across the globe.
This follows a recent pattern in other sports, such as gymnastics and swimming, where women have come forward to talk about recent or historical abuse from male coaches.
But in English football, a similar #metoo moment has not happened.
Culvin says she is not surprised if players have chosen to remain silent about past experiences, whether that is abuse or the consequences of a player-coach personal relationship.
She added: "We've got to understand it's players' livelihoods on the line. We can't expect players to risk their careers and talk about microaggressions if the procedures and frameworks are not in place, and there's not a safety net for them."
Other sources have told BBC Sport that people are unwilling to take a hard line on this issue, or act as whistleblowers, in order to protect themselves.
"Those in positions of power are scared to implement rules because of their own skeletons," one source said. Another said there would be plenty of people "looking over their shoulders" after the recent allegations in the US.
The FA told BBC Sport it encouraged "any player who is or has experienced misconduct or abuse to come forward and report their concerns" but recognised how challenging this can be.
The governing body did not provide numbers for how often its safeguarding procedures were used, other than to say there was a "regular flow of referrals" which remain confidential.
It added: "The FA fully investigates safeguarding and misconduct concerns and takes all matters seriously."
As it stands, clubs are encouraged to communicate codes of conduct to players. It is up to the clubs themselves to set the terms and monitor whether they are being met.
But several sources have told BBC Sport there is inconsistency across the top two tiers of English women's football, related to whether a club is closely linked to its men's team.
The FA insisted it is working to help coaches "better understand boundaries", including "where the line is drawn on banter", and has ensured coaches are required to undertake safeguarding training every two years, a change from every three years previously.
It also says it will be "reviewing" codes of conduct ahead of the 2022-23 season as it does every campaign, has "worked closely" with the PFA to ensure players in the WSL and Championship were "reminded of the routes to report concerns" and has developed anonymous player surveys.
The FA added: "There is always more work to do to support a player-centred culture in sport and football and we will continue to drive this messaging at every level of the game."
Culvin said there were still questions about whether the lessons from the Sampson sacking have been learned, and a need for the FA and other federations to be more transparent with their whistleblowing procedures and support for players.
"The stories are still emerging. A safe environment is paramount," she added. "Our voices need to be heard throughout the conversation and be centralised.
"Whether people learned from the situation with Mark Sampson remains to be seen.
"It doesn't mean just developing a policy and presenting it. The difficulty is actually implementing it as part of a culture shift. Have they set up a system where players actually feel safe to come out and talk about issues that might have emerged?
"What the NWSL did was progressive. Last year, the players said they needed measures in place for a safe and healthy work environment, the league acted on that and then released their policy.
"So I think it will be fruitful for the FA to publish documents similar to that of the NWSL to give an indication that they are taking this seriously. Maybe they already exist? But I haven't seen that published in the media in the same way the NWSL did.
"There's definitely a long way to go to protect the interests of players, not just with the FA in England, but across the globe."
Additional reporting by Katie Gornall