Obviously, there are worse problems than a guy saying "I love you" too often, but if it's a problem, it sounds like the two of you need to have a long conversation. You need to understand why he likes to say it so much: Is it because he's insecure or hoping to comfort you or just breathlessly in love? (Or some combination of the three?) And he needs to understand how it makes you feel. So, if it really bothers you, tell him why.