This is what it boils down to. Bisexuals don't fall in love and marry same sex partners in very significant numbers (I'm bi but I did, its not the norm).
Bisexuals- you can't have a situation where homos watch bisexual after bisexual after bisexual after bisexual after bisexual after bisexual after bisexual after bisexual after bisexual after bisexual after bisexual after bisexual they knew at college all settle down in hetero marriages and expect homos to have a really happy-clappy attitude towards it.
In 2013 Pew Research asked bisexuals who they were in a relationships with (so these are self identified bis). Only %9 said same sex partners. There are more heteros so off course more will be in opposite sex relationships but this number is so small its almost a joke. A few were in relationships with trans people. Even the the bi women who PREFER women in this study aren't even in LTRs with women!
Bis like to blame this on homos refusing to date them. Some research including this study shows bi women outnumbering lesbians as much as 2 to 1. You could date other bi women, there are more of you. Plus almost all lesbians have dated bi women and unfortunately some have had bad experiences and chose to stop.
There is a sexist stereo type all bis go for men. This is BS. Gay men don't even think bi men exist because the only ones they ever experience are transitional bis to a gay identity. True bi men are mostly in LTRs with women. There is just such a small number of true bi men. There are way more bi women (3-1 in some studies) so it is much more of an issue for lesbians then gay men. Bi men are a small group but they don't generally choose a gay marriage either.
Some gays feel like they are just there for bis to screw around with until their real relationship and this kinda seems to be the case. Who you had sex/relationships with when you are young isn't that important. It's who you are there for during holidays, job promotions, and cancer diagnoses during a lifetime. Most bis aren't really down for that with same sex partners once they are at an age where they are ready to settle down. You can't call me a bi-phobe, its just the truth.