How do you handle romantic relationships?

Like the title says, how do you handle romantic relationships?

Whenever I get even remotely close to someone in that sense I idealize them for a few days and then it goes all downhill. I get terribly paranoid and uncomfortable (perhaps even disgusted). I don’t really have a problem with being open about my issues with platonic friends but the one time I was in a “relationship” I completely shut them out.

At this point I’m OK with never having a partner (I think). I feel like most people would be too impatient with me and that it’s more trouble than it’s worth.