Good on you to reach out here to help better understand your boyfriend!
I'm going to say something I often tell others with DP/DR that is comforting to consider:
I'll use myself as an example here. I find myself, especially in the beginning and when triggered, unable to connect with loved ones, friends, family, pets, etc. It's especially frustrating and disheartening when a loved one goes through a major life event such as a wedding, birthday, or whatever, and there seems to be no emotion, no reaction, almost even void of numb. It can seem like one is a bad person for not FEELING anything, excitement, sadness. Even when a family member or friend or pet passes over and there's nothing, no apparent sadness, just guilt for not having any emotion about it. That's the kicker though, the guilt, the frustration, the existential LONGING to FEEL something. anything! That there, is the proof that we, who are dissociated, DO CARE! And deep down DO FEEL, even when our brains won't allow us to process or feel connected to others and things that are happening!
Because of if we really didn't care, it wouldn't bother us that we apparently feel nothing. And if your boyfriend plays it off and says "Well, no, I don't actually care that I don't feel the emotions", then he's probably just trying to avoid feeling guilty/bad about it (i.e. dissociating even more). I'm sure if he didn't really care and didn't deep down actually feel, then he wouldn't make the efforts to keep you two going as a couple. The thing is, being in a relationship while DP'd is WAY difficult! It takes work, and I've noticed those with DP who do succeed in relationships, it's because both people in the relationship want to make things work, and especially when the non DP'd person of the relationship actually wants to understand, give comfort, support and help cope.
That's just my two cents.