I think this is a syndrome I'll dub, lagged angelic-morphism.
When people first meet others of the opposite sex they usually don't know everything there is to know about a them, thus they're able to fill it all in with the traits that they think belong to the perfect girl/boy. I don't think you can truly know someone as a friend for quite some time; so I think you're attractions are still hitting along the lines of this time period of initial attraction.
Your situation is probably a combination of this and a slight oedipus syndrome since you weren't raised by your mother. You may long for love more than the average guy and thus it manifests itself in the form of puppy love encounters.
Start gauging the feelings you have when you start liking a girl. Record them so you don't forget them. Learn to be friends with a girl for a long time without confessing to them. See where that takes you.
Or, change your game up. If you can fall for any girl, only talk to girls you find attractive. Don't fool yourself into thinking you just want to be friends. Don't be afraid of disappointment. Just confess all your feelings all the time. Don't fall into that friend zone. Don't be a pussy. Don't fear rejection. Get into a long term relationship. Reaize how shitty and annoying relationships can be; and how being in relationships makes people act crazy. Then you'll be on the next level.