Sexless relationship

I can't satisfy me partner . I'm 35 and she is 33 . I've tried all sorts of medications and had my testosterone levels checked , which were fine . I'm now questioning my sexuality . I've had two same sex encounters before and although I never hated them my penis still did not work . I find my girlfriend very attractive and she means the world to me , but I feel I'm letting her down now and that she may leave . Am I a repressed homosexual ? What are the signs of such a thing ? We speak about things very openly so that helps . The other day she asked would I suck another mans penis and I said that I probably would I don't fancy men but I find penises attractive . At the same time I love female bodies but as I'm not performing for her I feel I might just be outright gay . I love her body and the smell of her body but I can't hey hard with her to have sex . I've had a long history of mental problems so that's probably not helping matters . I'm so close to letting her go now as I'm not making her happy . We've even tried porn to help things . She let me watch lesbian porn ... Which is amazing for a woman to let me watch , but it didn't help . I always Fantasise about another guy sleeping with her and me watching . How should I progress from here ? Am I gay ? I've met two guys before and I would do it again , my love for penis will get the better of me , but I don't fancy men . What is going on ? Please can someone offer any advice