What do I dooo

Okay so my boyfriend has a friend, who’s a girl. I know he’s loyal, I’m not worried about any sort of cheating. I have made it clear to him that I will never ask him to cut off friends for me bc I know that thats not fair. When we go out though, like if we’re cuddling or talking at a table in a pizza place, he’s having a full on texting conversation with her on the phone. I tried to tell him that when we have our one on one time, I want it to just be us, but he says it would be disrespectful to not answer her even if we’re out together. Before I could get the chance to tell him I want to find a compromise, he told me he doesn’t want to talk about it anymore. Help?