I'm in a relationship with the host but they've fallen in love with an irl person

I'm an alter, dating the host + one other alter (who the host is also dating), I love them but they've got a crush on a real-life person and it's eating me up. Nobody else really cares since only the host really maintains relationships with people (the rest of us don't care much about that) but they still have the crush and I feel really sad and cast aside.

Honestly the host gets crushes on lots of people, that's how we found our third person. It makes me feel jealous and scared of infidelity. They said they're not a cheater, but I know they still get crushes (but don't act upon them). What should I do?