When "sorry" seems to be the easiest word, then you might want to take a closer look at what's going on in your relationship. Apologizing when you've truly committed a wrong act is honorable; saying you're sorry when you're not or apologizing for the most innocuous infractions may indicate deeper trouble. Research has found that people who are chronic apologizers have lower self-esteem than those who apologize only at appropriate times. Listen to yourself when you're saying "I'm sorry." What are you sorry about? That conflict has arisen in your relationship? Are you trying to please or curry favor with your mate? Do you apologize simply to resolve an argument and smooth things over? Truly examine why you feel sorry - or if you're just paying lip service to keep things copacetic between you two. Apologizing in the middle of an argument is detrimental because it can leave issues unresolved.
When you say you're sorry in order to end the fight, then you may leave issues simmering beneath the surface - an unhealthy situation for both of you. If you're not sorry for something you've said or done, then say so! Apologizing to remove yourself from the negativity of the situation or to please your mate won't get anything accomplished, and it can reinforce negative feelings about yourself. Instead of reflexively apologizing, try stepping away from the situation before uttering the "s" word. Take a walk or a drive, and reflect on potential solutions to the problem. Give yourself a break from shouldering all the blame, and you'll begin to love yourself enough to stand up for yourself when you need to. And that's nothing to be sorry about.