Note: Maybe a moderator can merge this.

I also have troubles 'believing' in friendships between people that are attracted to each others sex.

I mean, if you are friends you are both attracted to each others personality. Is it really possible both of them are repulsed enough by the other person's looks to never considering it being more than just friendship?
Almost always, there is at least one person who wishes it was more.

If you have this opposite sex friend and suddenly you both become single, are you sure neither of you will consider it? And if not, why not? I understand one person is not attracted to the other. But apparently the other is, and the person not attracted keeps him/her around?

I don't mean to say it can never 'work' or that it shouldn't be done. But I find it hard to believe most of these 'just friends'-relationships are just that.

I can't say I have had good experiences with it myself. I tried to be friends with a girl I deeply loved. She kept me around, kept inviting me, she told me she couldn't see any romance between us and never suggested otherwise with her behavior, and I wasn't able to engage in romance either way (too young/naive/insecure/confused). And every so often, when she was single, she would hint at casual sex. Either to test me and my intentions, or because she was really interested in that, I don't know. This went on for years. I even had two 'dates' with her and her now husband. It was the three of us meeting, doing some activity, having dinner, and me staying over for the night.

My best friend thinks she is a bad person for having done to me what she did to me.

The only case I can really make for a male-female friendship is one where you have so much history together already, that it is a shame to give up on it. Two people growing up like siblings. Or a case where one is in love with the other, wanting more, but is strung along, and over time these feelings and pains erode and the situation is accepted as both have their own different romantic interest. Seems tricky. I guess you need to get to a point that it is clear the romantic option is gone because it was tried and it failed and both agree on this. So there's no point in trying again. And if you still respect each other and have some stuff in common, and maybe deep emotions shared, then maybe staying friends is worth it.

As for the woman in my case. After not seeing her for 6 years, I emailed her 6 months ago. I send her a Facebook message two months ago. I got no reply. The last contact we had was from her to me. It is 14 years in the past now, but for many years I have deeply desired to know how she experienced all this.

Also, the female stringing along the completely infatuated male for ego boost, I have heard some females describe it in another way. They call it 'friends you cannot trust', because you suspect they want more. I guess one can debate who is the victim in cases such as this. In that interpretation, in my specific case, I was the one to blame because I decided to try to become friends when deep in my heart I wanted more. She could not trust me. And I struggled so so hard to keep my feelings in check and to keep our friendship pure. I refused to engage her in banter about sex because I knew she wasn't interested in me romantically and I didn't want to ruin our friendship. But I guess in this interpretation, I was the one tricking her.

So to the OP, don't be so sure the other person is fine with being 'just friends' just because it appears that way.
When you get really close, because he becomes your male girlfriend, and you are hurt emotionally, you go to him, you get drunk together, you hug for comfort, he makes a move and you reciprocate because you feel weak/confused/need an ego boost, is he taking advantage of you? Or is it him taking what he wanted all along and you refused to give all that time?
When you wake up, will you regret it and blame him?

Bit of a hypothetical, but I have seen this come up here. And I guess it is a common theme.

I pride myself in being really strong. But I was deeply in love with the girl I described. I don't know what I would have done if one evening, I found her in my arms, crying, drunk, cursing her ex boyfriend, and suddenly kissing me. One reason I never drunk alcohol with her.

This may be why my friendship with the woman I described finally ended. Her husband must have wondered what was up with me and her friendship with me. They must have discussed it. And she must not have had a good answer. I doubt she would have told him "He is deeply in love with me. But he has little friends besides me and I like him. Yes, I find him physically attractive, but nothing ever happened between us, and never will." She must have made up some excuse and he must have called her out her ********. And I stopped being invited. That's how I imagine it happened, but of course I don't know. I might be totally wrong.

That said, the husband being jealous is not good. I mean, the questionable part is the moral aspect of the two 'just friends' people. Who is tricking and hurting who? Not the husband being cheated on, because he isn't. You aren't cheating on your husband by keeping attractive potential partners around. Until of course you do engage with them romantically.

I don't know if bring up his (former?) female friend up is a good idea. He might have been into her more than he was ever in to you.

That the man always wants to sleep with the woman, I'd call ******** on that, were it not that I am very different from most men. I mean, I proved the opposite. I refused to sleep with the woman I was deeply in love with and who rejected me as a romantic partner when apparently she did want to sleep with me, despite knowing I had feelings for her she never showed me she shared (though I can't be sure), or at least wanted me to believe she would (to boost my ego?).

So I'd like to call ******** on that, for the sake of all men who are similar to me, however low their percentage may be. I really find it hard to believe a man would stay friends with a woman just to get a shot to 'score'. They just must be deeply infatuated. Not saying the wouldn't jump at an opportunity for sex, but then it would be a means to an end, not the end itself.
I do get the feeling that in most cases it is not the female being in love with the male, and the male rejecting, but the other way around. But I have no empirical evidence for that and I feel the bias of my own experience. I also feel that a male wouldn't want to be friends with a female they do not find physically attractive enough (to sleep with), regardless of being in love or not. Everything the female does is nicer, smarter, more interesting and appealing if he finds her physically attractive, and her affection will feel warmer/more special. But I don't see how that means that the bottom line is that he just wants to put his **** in her.

There's more to masculine energy than just that. Maybe it means he will jump in front of her when a robber points a gun at her. I am not sure I would risk my life for any male friend, no matter how close I am to them.

This idea that a male stays friends with a female for years, to then have sex with her for one night, and to never talk again after that, that makes no sense to me.