The show is about something, it's about every day life. This every day life has been tied together by Jerry. Jerry has dated like crazy, but never found the right woman. His character could meet the right girl a few episodes before the end. Then he could get married, even before the last episode. Then like in real life, he would be too busy with couple things and they would go their separate ways!
This would accomplish two things: 1) The wedding/reception would allow most of the past characters to appear one last time with a memorable statement that reminds you of past episodes. 2) If they don't want a final ending, this would allow for a follow up series or movie with Jerry becoming single again and the gang getting back together again.