Half-hearted convert

I have a friend who was in the process of converting to Judaism. He was very active with Hillel and we welcomed him as mishpachah with no questions asked.

Recently he got a new girlfriend, has fallen out of Jewish life, and has been making posts of himself preparing for Christmas with her.

I feel disappointed and hurt. We welcomed him into the fold, and he loses interest on a whim. I’m not even religious, but I guess it hurts so much because the rest of us don’t get to choose to be Jews or not.

I’m really upset in a way I didn’t know I could be, and im not sure if I should even bring it up with him or not.