so confused. can anyone explain?

I'm 25 and female. I have been in a relationship for 3 years and only ever been with guys. My boyfriend I don't see for like 7 months in a year as he works away, beginning of this year, a couple of weeks before I was due to see him I started feeling like maybe I didn't care if he cheated on me (because that was always a fear of mine while he was away) but I know for sure I would be hurt if he did. It was a strange feeling. I started fantasising about girls a lot while masterbating, and then it became more and more and I started to worry if I was actually a lesbian. I don't find girls attractive when I'm walking down the street etc, it's just when I'm masterbating. I love my boyfriend more than anything. I just spent 5 months with him and didn't want him to leave again. But he has a high sex drive and comes pretty quickly so most times I don't orgasm. Am I lesbian or bi? Or is it just a fantasy? I'm scared if I was to act on it, it would turn out I enjoyed it more and I would turn lesbian, but I don't want to act on it and I don't want to leave my boyfriend. While I was with him I never thought about girls, but now he's gone again it's started again. I'm so confused. If anyone can help me.

i think it's just a fantasy.

Your mind is just acting up because he left. Being lesbian or bisexual means not only to be able to have sex with the same sex but also have emotions and attraction to the same sex. If you only think of them while masturbating, its fine, trust me.

I think you're mind wants what you feed it, you are probably not currently bi. If it bothers you to think about women then just focus on men and eventually it will flip back.