“I’m wondering if there’s always a stage where the question of taking it into a different realm (love and/or sex), and if so, how do the friends navigate thought that?”
– Not always: Sometimes there’s mutual sexual disinterest, absence of sexual chemistry, OR mutual lack of availability or circumstances. Also some people are content with their current situation and not looking and so it never really comes up.
“Or does the friendship develop the same way as friendships with folks of the same sex, and love and sex are never an issue?”
– Yes. Which is another way of looking at my answer to the above sub-question.
“In either case, how does it happen? If you have experience with this, please tell us how you got into it, and what were the problems you faced and how did you overcome them?”
– Ok, first, I have to say that it actually happens quite frequently and naturally, and why it occurs that way for some and not for others, I imagine, is largely because some people have a set of preconceptions and apprehensions, and others don’t. What makes it strange or difficult or whatever to befriend the opposite sex is one or the other person involved thinking it is strange or difficult or whatever. What makes it not those things, is the absence of such preconceptions and apprehensions.
Another thing that helps is if people don’t have interpersonal love confused or combined conceptually with romantic and/or sexual love.
example: I meet a woman in a class, we have friendly, open conversations and like each other as people, and find we have things we like to talk about and/or do after the class concludes. Romance with each other never really comes up. We hug each other as friends, without sexual tension.
other examples: We meet and talk, get romantically interested or even involved, then one or the other or both discuss and decide to stop the romance, maybe not see each other for a bit, or not as much, then later continue communication and even spending time together as friends. The context is clearly that we’re with other people or romance doesn’t even come up because we completely resolved it before, and we know if interest and opportunity came back, we could and probably would talk about it again.
Tension and misunderstandings mainly seem to happen when there is some kind of breakdown of communication.