How do you tell someone?

When they are in a bad relationship. Like she hates your friends when you choose to hang out she gets mad and leaves you sitting somewhere for 5 hours. She doesn't make an effort but you damn well better be making an effort for her. Your going through school but she wants a tiffany's engagement ring. You want kids more then anything in the world, the person you hope you'll be having them with doesn't. How do you tell someone this? do you not and watch. Hope its not too late?