How do you know

How do you know when it’s time to walk away from a marriage? I know I don’t love him and we are SUCH opposites but we’ve been together 10 years. That deserves effort but at the same time I don’t want to waste my own years of life. He doesn’t beat me he doesn’t do anything crazy it’s just simply were such different people that I just don’t feel happy free or complete with him. But we have two children in the mix and it’s not really fair to them to break up an entire family just because I don’t have someone that is free spirited as me just such a crossroads because he’s not a bad guy he’s just not the guy for me