>>Anyway, this guy hung out with other gays for a year or so, until one of the more attractive young women in the department latched onto him. Once he started swimming in the sea of heterosexuality, he never looked back, and they were married with several kids. I last saw them around 10 years ago, and they appeared to be going strong.<<
Isnt that pretty much the definiation of bisexual? It sounds like he was attracted to both.
Those of us who were straight in the dept. knew we only liked girls, and were never confused like some guys. Whenever we straight guys heard a new guy say he "wasn't sure whether he was straight or gay", we'd always say "well, if you're not sure, we're sure: you're gay."
I only mentioned this one guy as the only example I could think of concerning one who'd left gaydom and never looked back. At least he's the only one I ever knew. I did know other guys in my theatre days who were definitely bi, though.