Confession time: seeing a woman get off to gay porn - either in person, or simply seeing it on her fav's list - really gets me going . Even hearing a woman mention that gay guys turn her on will cause my cock to start growing inside of my pants.
There's a few reasons I love this.  First - it tells me what a freak she is.  I instantly imagine her frigging herself, as she watches some bottom get slammed as his cock swings about, spraying precum everywhere. Abandoning her pussy to play with her ass, when she really gets into it - her pussy spraying a mess on the carpet, as she watches the bottom stiffen up and spray a mess of cum on the floor.  If she gets off to seeing a guy grind his prostate on a cock until he comes - it means she'll be down for just about anything!
Second, it tells me that she gets off on making men cum.  I love playing with women - seeing them orgasm, tasting every bit of them, invading their most private spaces with my tongue - but if she's also getting off to gay porn when I'm not around, that tells me she won't be afraid of doing the same things to me.  I won't have to ask her to tongue my ass - all I need to do is lean forward and spread my cheeks, and she'll be moaning away as she buries my tongue inside of me.
Third, it tells me she loves animalistic sex.  Sex between men is more aggressive , ususally, than between men and women.  It means she knows what she wants, and she isn't afraid to demand it.
Fourth - watching it with her feels so dirty.  I once put on an amateur gangbang scene for a girl I was seeing, and had her lean forward on the seat, her ass exposed behind her.  I told her to describe what was happening on the screen - and why she loved it - while I buried my tongue in her cute little ass.
A lot more women admire gay porn than openly admit it (I used to fix computers for my friends back in the day - right after they 'leant it to their gay friend who downloaded all the viruses'). Let your freak flag fly, ladies.  Even if your man doesn't want to do an MMF - I can almost guarantee he'll get turned on by learning what a freak you are!