Is it normal that i'm much jealous of people i like

I usually notice and like (by like I mean "they seem cool and I'd like to speak with them") people who are alone in public, because that makes them more relatable to me, the fact that I could have something in common with these people makes the idea of talking to them way less scary. So when they join their friends or just do something I wouldn't, that feeling of liking becomes jealousy, I still think they are cool, but I don't want to be with them, but a little like them.