I think you really need to sit down and talk to your BF.( He sounds a bit controlling in a way and that can actually lead to bigger problems if you do not say something now.) Also to me a gift with strings attached and only 1/2paid for by him is really not a gift to you at all. Since you both paid 1/2 then I think that you both should come up with a name you both like.
I named my first Yorkie, Jeter, he was a gift for my birthday/Christmas from my husband. I was the only one to name him, no one else had a say in it
But Axl and Yumi Yasha were named by us all compromising on the names. In the end Axl does have a Yankee name in his full AKC papers. My girl Yorkie has a Japanese name, they wanted Yasha I wanted Yumi so we combined what we liked and came up with Yumi Yasha.
Also if this helps any, my husband was not to big on Jeter having his hair up in a topknot and him having outfits too, until I put a Taz sweater I made from my kid's no longer in use sock and put his hair in a blue hair band. Once he saw that his outfits were "boy" outfits and not "Girly" in any way he was fine with it
Best of luck to you! keep us informed how things go!