Dating help

I really like this guy and we’re dating. We do have stuff in common but are different in other areas. I mean I get him out of his comfort zone and make him try new things.

I’m really attracted to him and we have great chemistry...but for some reason I keep making up scenarios in my head that he would rather date my friend just because they have similar interests (movie tastes, and they both love dogs). They both don’t really like to travel and idk I’m like....wait should they date instead????

Why do the voices in my head keep doing this to me???

I mean he likes me and I like him and we’re dating. So why do I keep picturing him with my friend it’s soooo weird?