There’s nothing wrong with seeing the good in others. It’s an admirable trait. Never forget that.
To some extent, I can relate to how you feel, though, because I have the same problem. In my case, it’s because I think better of others than I do myself, so it’s easy for me to idealize a person. I just got over a crush recently, in fact. How did I do it? With a good, strong dose of realism. I reminded myself of the reasons why the crush wouldn’t work (i.e. incompatibilities in our personalities and interests). Also, I recognized that he seemed so perfect to me because I knew little about him. When I see him, I still get that fluttery feeling inside, but I can enjoy that now without any expectations of dating him. That’s because I gave myself permission to be attracted to him, but I’m aware that he may not be the person I imagined him to be.
Although my methods make the crush control process sound easy, sometimes it can be hard. Usually it works best when you recognize signs of a crush early on and respond quickly with gentle, corrective self-talk.
If you have any questions, feel free to PM me. Good luck!