Someone who is usually quite a party animal is going to be much more introverted than usual today, but don't let it throw you for a loop. They just need to go back into their shell for a while and think some things through. Things are changing in their life, and believe it or not you are an inspiration for some of that change, so stick with them through this period. This is your chance to be someone's personal cheerleader. Get out there and give them a hand.