I don't have DID but I have had plenty of relationships where only a part of me was ever really involved with the person. I too easily walked away from them and I think that it was this compartmentalizing that made it so easy.
I also tend to get involved with people that eventually become abusive towards me when I don't do what they want. The part I usually share is compliant and people pleasing so people that like to feel in control of others tend to be drawn to me (or the outward part of me). But the rest of me that doesn't like being controlled eventually walks and the compliant people pleaser recedes until next time...

I feel kinda bad because I know the people that befriend me (they always pick me) have abandonment issues and I certainly don't help! Still, they do become abusive. Idk, it's complicated...

I also wonder if you will see this as a relationship that was better to have left in the future.

I absolutely don't think you're a bad person. And, some helping professions like doctors benefit from little to no emotional response. Your lack of feeling could always be put to use for "the greater good" if you're concerned about it. I bet you can give good advice!