She was engaged to another guy...but she made the first move
I had dated a girl, M, in my late 20s for a few years. I ended it because she wanted more than a casual relationship - but we were still into each other (she was more into me than I was into her).
Fast forward 5 years, we are in our early 30s. We had remained friends after breaking up, even flirty - she was still very much into me even through we both dated other people - and shared about all our relationships with each other. She was dating a guy for a few months, told me she just wasn't that into him, but he treated her nice, and she wasn't dating many others at the time. She tells me a bit later she is thinking about dumping him so he isn't led on. She didn't "see a future with him." Yet the next time they see each other, he proposes to her.
She tells me and I say - wait weren't you thinking about dumping this guy? Why would you consider agreeing to marry him? She admits she is scared because most of her girlfriends are already marred and doesn't know if it'll happen to her. I told her that isn't a good reason to be married. I had seen friends and family marry somebody for similar reasons - and it always ended in divorce.
She asks the guy for a few weeks to think it over. She decides to accept his proposal. I was floored, but supported her decision though I did not agree with it.
A few weeks after she got engaged, we go out to a basketball game - just the two of us. This was planned before she got engaged. During the game, we both step out to use the rest room before the end of 3rd quarter. Up to that point, things has been chill and flirty as usual. All of a sudden, she pushes me up against the wall and started making out with me. I return the attention as I am still attracted to her (athletic body, great personality). We are in a public hallway, but nobody is around and we continue to make out until the quarter ends. She pulls back, looks me in the eyes, then goes to the restroom without a word.
We get back to our seats and begin watching the game. She tells me she wants to get out of there and I agree. She drives back to my place and on the way, admits that her fiancee has no idea she is with me - and has even asked she not see me alone even through we have been friends for years.
We get to my place and park, still talking. She admits that she still wants to be with me, and still thinks about me whenever she has sex with somebody else. I ask her why she didn't talk to me about it for so long. She tells me she was scared of losing our friendship, and would rather be a platonic friend than not see me anymore...but getting engaged is conflicting her because she still wants to have me in her life. I ask her if she loves this guy, she doesn't answer. I ask her if she still wants to marry this guy, she doesn't answer. Then she looks at me intently.
We go into my place and sit next to each other. She tells me, You already know what I really want. She kisses me passionately and we end up having amazing sex. The next morning her fiance calls. She answers and tells him she was out late and won't be available for the rest of the day. We then have sex again.
She left later that day, and we never talked about that night again. She married that guy and they are still together years later.
She still flirts with me when she get me on the phone by herself even now, over a decade later...