He can't make up his mind!!

So this guy I'm with can't make up his mind. He's been with this girl for 5 years now && now he wants to make a Life with me but he's still with her even though they aren't close and the relationship is on the rocks. But he keeps saying he doesn't know what to do cuz they've been together for so long. 
What's should I do, stay with him or just move on??