my bf has a crush?

Me ( F 22 ) and my boyfriend ( M 22 ) have been together for more than 2 years and he has now dropped a bomb on me and i don’t know how to react or how to feel. we were just having a late night talk, as we often do, and he just asked me if i ever had a crush on a guy while we were together, if i ever thought “he’s the one” or felt like i was in love with someone else. i honestly thought about it and i don’t think i ever did. when i asked him the same question he said he did, that it was a week long thing kinda, and that he didn’t do anything about it. he told me who the girl is (i know her too, and she just enters our friend group). i’m so confused. i trust him, i know he didn’t act on it, but what do you mean you thought about it for a week? to me it’s just insane. i’m not saying i don’t even look at other guys, i can say they’re hot but that’s it, it’s not like i think i’m in love or that they are the one. after i asked him to clarify if he actually ment in love or just like a crush he said that he meant the latter (of course because what do you mean your in love with a girl that you don’t even know and while you have a gf). he says that it’s a normal thing for gays and that he told his friends and they all had the same thing happening to them, but of course they didn’t tell their girlfriends. i guess i just need to know if it’s true. i feel so insecure right now. i can’t wrap my mind around this.

sorry for the typos and mistakes english is not my native language