According to Jim: The Six-Week Curse

Andy is convinced Emily is going to break up with him since his former girlfriends all left him after they'd dated him exactly six weeks. To get to the cause of Andy's former break-ups, Dana hypnotizes him and discovers that he sabotaged every relationship due to low self-esteem. With Andy still under hypnosis, Dana boosts his feelings of self-worth, but his new-found confidence backfires when he flirts with every woman in the restaurant while on his sixth-week date with Emily.