This may sound harsh and too close minded, but it's impossible to stay non-sexual friends after a sexual relationship.
Only time that happens is when one person (usually the male) has hopes for future romance and the other (usually the female) strings them along, becuase of the numerous benifits of having a guy "friend" without having to give anything in return. The females will usually have no respect for those men that become their friends, which is why they decided to make them "friends" in the first place.
This is also usualy true the other way around, but happens much less often when the male is the "stringer".
Those are the people they basically use, and may even enter into relationships when they are out of options and are desperate/lonely. 99% of those desperation relationships are just that, and never work out in the end just to leave the "used" party even more emotionally disfigured.
Search Google for "ladder theory"... It's a very cynical and one sided view of things, and is to be taken with a grain of salt, but has some undeniable truth in it.
Friends to lovers happens on rare occasions, and even works out on rare occasions. Lovers to friends happens often but only to result in loss of contact anyhow. They will talk and stay friends, but when one or both find someone else they will slowly drift apart and cease to communicate. Or one of them is still alone, in that case they will be the nagging ex looking to fill some emotional void.
Males tend to be effecient creatures. And if thought of logically, there is no reason to keep an ex as a friend (at least a close one) around.
This is just my theory on things. I have experienced it from both sides and upside down and can say for a fact that pleutonic sustained relationships between males and females cannot exist.
