Future plans: You want kids. He doesn’t. You want to have a career where you travel the world. He’s okay with staying put in your small hometown. If you want a guy that’s going to be around for the long haul, make sure that your plans for the future align. They don’t have to be perfect, but make sure that you guys envision a somewhat similar future. Maybe he wants three kids and you only want one. You can compromise: two kids and a dog.
But if he doesn’t believe in marriage, and you know you’re never going to pop out a baby without him putting a ring on it, you may want to reconsider.