I have been dealing with some different relationships lately and the levels of commitment that they are at. I have always felt that if you are going to commit to something, you should do it all the way, or not at all. Don't even bother if you're only going to do it half assed. Especially if it is a relationship commitment. People get hurt and sometimes relationships and trust are permanently damaged.
Perfect example: when I adopted my sweet kitten I understood that it was a forever commitment. It wasn't just for when it is convenient. It's not just for when she is cuddly or playful. It's for the hard times too when she's obnoxious and bites and gets sick or chews my belongings. She trusts me and she knows I will protect her. I saved her from 'the cage' and she never has to go back again. Not ever. I have committed to taking care of her, loving her, to get her the care she needs, and be there no matter what. We're a package deal and you can either like it or walk away. She's my best little friend.
People's relationships should be more like that. Commit to make the person you care about your first priority and make them as happy as you can. Care more about them than yourself and you will be successful. And make sure they will do the same for you because there is nothing worse than being more invested than the other person.