Do fish fight??? I know it’s not a fur baby but this is the only “animal” group I have

Okay so this may sound like a SUPER weird topic but this is a legit question I have. So I really like having fish. Not going to lie I have a small ass tank. It’s 3.5 gallons and I do plan on upsizing to a 5 gallon when I one have the money because I’m 17 and broke, and two find the space in my room because it’s small and cramped as it is. Anyways I like to think I’m very considerate of animals and I always end up feeling bad for having fish because they aren’t like a dog where you can tell when they are hungry or whatever. Anyways I got two molly fish, one black and one white. They came out two different tanks in pet smart and the man said they should be fine together. I usually get guppies (2 at a time) and he said it’s best to get 4 because they are grouping fish, which probably explains why my previous guppies have ended up dying a week after and the two guppies I’ve had in my tank never acted like this. Anyways the white molly (bigger fish) chases around the black one who is usually hiding behind the filter or the one plant I have in there and stays closer to the rocks. At first I thought they were playing but now it seems like the white fish is bullying him. It may not seem like a big deal because they are just fish, but I honestly feel really bad and don’t know what to do😂😭 should I take the white one out or would the black one get lonely??? Idek