Let me tell you for me this is mostly a side thing. Not like a fetish that I like on the side but rather part of something bigger of who I truly am.
I can't say for your boyfriend but for me I do have problems with my parents but I'm sure others have the same problems as well. It's not like I was abused or spoiled/sheltered. It's just something that I've developed and part of who I am. Maybe though, you should set some boundaries and limits as well as talking about it to find out the underlying things to try and understand each other more.
For me though, the girlfriend/wife/mommy (during playtime, not biological) of my dreams would also have other interests than infantilism. You can't just focus on the sex or you'll burn out like most college couples that are only in it to "shack up" with each other. I had a girlfriend that I had to break up with a while ago (surprisingly we actually didn't have any sexual relations, the closest we got was to "second base" because we respected each others boundaries and wanted to see if we enjoyed each others company without the sex). We definitely clicked and liked each others company but it couldn't be because of some things that were happening in each of our separate lives (that being said it's not entirely set in stone and if we happen to decide that we can be good together and it's the right time to be together to deal with our individual hardships then we'll pick it back up). Keep in mind though I haven't told her about any of my fetishes or anything but I think that she had an idea of what I liked because of the way we were when we were alone together and I had a feeling that she was kind of turned on by those kinds of things (she knew that I had a thing for spanking though).
This is just my experience and you could probably use it for a case study or anecdotal evidence but I highly doubt you'll get any quantitative results from a thread like this. But good luck with your boyfriend though, I hope you have a wonderful relationship.