Life happens, we all get that. For me, it's mostly work that happens which interferes with my ability to attend both practice and dance class. The key is to not make it a continued habit, and to keep in communication with your dance company team. Knowing you will miss rehearsal means it's up to you to find out what you missed, and to make sure you are prepared for the next rehearsal. It's true that when you are not there, you are missed - particularly when working on staging a number or honing a dance just days/weeks before a performance. Most fellow dancers rely on seeing you dance in your designated spot in a choreography, figuring out their spacing and gauging their moves based on your moves.