I get why you'd feel like this. The way I see it, we have more control over our "relationships" with fictional characters. And since they're fictional we don't have to deal with a real human's personality and all the bad things that come with it. So it's easier to care about a character especially if you relate to them or project onto them. But real people are too complicated and they take up too much energy so you distance yourself. Specifically as an INFP thing, this reminds me of our idealistic tendencies. Fictional characters are generally more attractive, powerful, kind, funny, etc than real people. And detachment can come from caring too much for too long. Infps do invest a lot of feelings in others and ourselves and overspending empathy can lead to burnout. Of course this applies to anyone but infps tend to be more empathetic and emotional that most types. I don't know you well enough to say this is what is happening to you, but I know other people have experienced things similar to what I just described