Because he probably has feelings for her, that usually happens when 2 people are together. Most guys usually don't cry over they're girlfriend, But guys are different. But they have feelings for that person, and if something happens, he is going to get upset.
if you could tell me why you cry yourself to sleep, then i could determin if you are a emo........ do you cry yourself to sleep because of a bad releationship, or you are not enjoying life because it's dull and everything happens to you. You tell me and i could work out if you were