Shit happens and in your case, literally. Speaking as a bottom, it takes time to get ready for you tops. You need to give your bottom some time to prep. If you book last minute appointments then you'd better be ready for such accidents. However, it is also up to your bottom to declare whether he's good to go or not. There are days when I have to pass. As good as his dick might feel inside there are times when I have to admit that it's not gonna happen that night. There are other stuff you both can do. Those I've had to turn down have been surprisingly more understanding. Sex have been much better since then because they know they don't have to worry about accidents.