Agreed. Coming out to a crush has never helped me personally as it was pretty evident they weren't showing as much interest in me as I had in them. For me, crushes have always happened when my exposure to the person was one-sided/parasocial (as seems to have been the case in your lesson). I have found that the most effective way to prevent this is to get to know people that excite you on a personal level before a crush can develop. This usually means enthusiastically trying to interact with them moment I notice them and abandoning them if it does not work out — instead of watching them for a while and then deciding whether to approach.