Friendships are all about acceptance and support, so don't succumb to pressure from a pal who is being too demanding about how much time you spend with them. If they can't understand that you just can't hang out when they want to hang out, then you need to reevaluate their role in your life. You cannot rearrange your life at the whim of other people, no matter how important you think they are to your life. They'll get along fine without you: assure them of that.