It does happen, but with risk
[QUOTE=WestLain;4308228]I am certainly not one who is judgmental regarding our activities. The only comment that I will make about this situation is that I have found, for me, that I have to keep these SA relationships on a business level, especially as a married man. So for me, that means treating the SB's as I would escorts. No long term relationships to f. Me up.[/QUOTE]My own experience was a close match to JoyDrop except that the ending was much, much messier for me. But for the first four years of our five-year relationship (I was married but am now divorced), it was an absolutely out-of-this-world experience. Everything from the sex, to the teamwork, the effortless companionship, the mutual emotional support. But we both fell hard for the unrealistic thought that we could have a life together, which once that started to become more of a tangible thing, the more unstable the relationship became. And it did not end well. That said, I do not regret the relationship, it was pivotal in my life. I only regret not having the perspective to have made different choices at various inflection points late in the game.
I'm now with a new SB, this one poly, which is a lot safer from a getting-in-too-deep perspective. While obviously I can't exactly be in her social circles, she otherwise considers me me as much of a partner as anyone else she sees seriously ("partner" being poly-speak for a relationship with emotional and physical components). It took her awhile to come around to acknowledging and accepting that she felt this way, as I don't think she considered that to be one of the likely outcomes. We now accept that we have a legitimate, caring relationship, but also that once she finishes grad school her life will likely branch off in other directions. I don't look forward to that, but I'm also not fooling myself into thinking it will have any other outcome. And she's one of the most emotionally and relationship-intelligent people I've ever known, so this time around I feel safe in the assumption that our parting will be bittersweet but amicable.
So it does happen. All depends on what you're looking for, and filtering your pots accordingly.