I broke up with my girlfriend because I don't have any time for dating.
Was there another reason? Or you just didn't have time?
Yeah, it makes sense to me.
Relationships require work and while there can be some exceptions made when you are very busy over short periods of time, it isn't appropriate to neglect making time for a significant other. You deciding to end things with her because of that makes sense, but I'm sure it was a tough decision.
Sometimes I feel bad, but she could be hard to deal with.
It sounds like you made the best decision for yourself, I hope you were honest in your explanation to her. If she knows that you didn't have time to devote to the relationship, I'm sure it will help ease any pain she's going through.