Any chance of finding true love? I was born 17th July 1985

So I've been seeing this chick for like 8 months now. It's been on and off but it doesn't seem to be going anywhere. She never asks me to stay at her place and I never have. She always stays at my place. I go to work during the day and she just stays home with my brother playing xbox and watching movies. I know she likes to work out with him coz when I get home after work they are usually sweaty, out of breath and one of them quickly runs into the shower naked while the other gets changed. I don't mind, it's good to know they get along so well and they are keeping in shape. But I feel she has been a bit distant from me lately. We don't have sex any more, and when we argue she goes and cries to him and lock the door. I know she is upset coz when I try to go to her she is moaning. He must be telling her something to help as she always says yes yes like that. Sometimes she gets so upset she says in there the night so we don't argue any more. My brother is a great guy helping us out like that. But since I feel we are drifting apart I just want to know how to break up with her and wanna know if I will find true love again... or should I propose and make her happy?

Please help and tell me if I should stay and propose or look for a more true love