I’m busy with x,y and z but what about two weeks from tomorrow?
Maybe it wouldn’t make perfect sense for him to bring you to his office party, his friend’s birthday or whatever. But, come on: when you like someone, you want them with you everywhere! You don’t feel they are a burden to bring along. You feel they enhance the fun. If a guy likes you, he doesn’t find reasons you shouldn’t accompany him places. He looks for reasons why you should come along!