<human>: Can you provide a brief overview of the text?

While in a relationship with him, we acquired pets. 3 dogs. Broke up; He eventually got in a new relationship and they got a dog together. 

Due to circumstances, I've taken care of them all at my place since he was out of state for a few months with his gf. Since they moved back at the end of last year, he's asked me several times if he can HAVE (not SHARE) one of the dogs. Dogs he didn't care to inquire about until he moved back. Not to mention, I was the one caring for them more. 
Why won't he let it go, or agree to compromise? I'm not willing to give up any of them completely. 

This makes the 4th time he's asked through third parties asking me to give him the dog. Every time I've said no or ignore it. 

It just keeps coming up. What's his deal?
<bot>: Ex wants one of our dogs, not sharing custody, but wants me to give him up. I refuse. But he wont' drop it.