What to do when your friend's friend is uncomfortable with him hanging out with you?

One of my closest friends happens to be gay, and that's never gotten in the way of our relationship before. I'm not homophobic, and as long as we have fun and make each other better people by being friends that's all I look for. However, he recently stopped answering my texts and deleted me on Snapchat. I emailed him and asked him what the problem was and he said his boyfriend (who he's had for a year) was uncomfortable with him hanging around another guy. I've established with his boyfriend that I'm not gay and won't go after my friend romantically but he still doesn't want us hanging around each other.