You're not one to stay in a relationship that isn't going anywhere, or one in which you're being mistreated; you've got too much strength of purpose to do that. Your ideals in love are strong and defined, but you also have a healthy sense of the reality of relationships. You won't allow yourself to be walked all over like a doormat, but you've got the discipline and strength needed to weather through difficult times with your lover.
And those hard times will inevitably come, because you're not one to cut and run when the going gets tough. When the time and the person are right, you're willing to make a commitment, and you'll stick with your honey through thick and thin. You do tend to be somewhat cautious in love, which is generally a good thing; it's better to take your time when you're trying to figure out if someone is the right person for you. Once you've gotten to know them well enough to make your choice and your commitment, you're in it for keeps. This quality will really help in your long-term relationships, even if it does make you come across as a bit emotionally reserved -- something a sweet and sympathetic lover can coax you out of.