It’s totally normal for a friend moving a distance away (or to a new floor) to ask for a number to keep in touch. However, because he has a girlfriend I caution you to not get too attached. This seems like a major time in your life so the people you meet will be extra special to you. Try not to get overly attached if it will end up with you getting hurt. Keep contact simple so you don’t get overly connected. Best of luck. Hope this helped.