I have always thought of myself as straight until a couple of months ago. I was in bed with my boyfriend (I'm a girl) and he gave me my first orgasm, and while he did it I had the image of a naked woman in my head. Then I went home and over the next few days I tried to give myself an orgasm and was successful but only while watching lesbian porn. I love my boyfriend very much and he can really get me going, but I can only reach that max pleasure when fantisizing about a woman on top of me. I don't understand why and what this means. I don't know what I should do about it.
It's not unheard of for a straight person to have gay fantasies. If you're attracted to, and have feelings for your boyfriend but also feel attracted to women then it could be that you're bi. Is there any reason you may be suppressing your sexuality? That happens quite often.
Maybe your brain somehow associated the pleasure of orgasm with thinking about that women, whereas it might well simply have been a coincidence, humans have hundreds of thoughts every minute, most of which they arent even aware of. Otherwise, you might simply be bi-curious. If you've never had any same-sex attraction before and you really love your boyfriend both sexually and emotionally I wouldnt stress out too much. Just go with the flow and see what turns you on in the future, who you feel drawn to, without judging it, without overthinking it, just observing what happens.