Ship-Jumper
(n). A person who doesn't like his or her surroundings or situation, and wants to leave a certain area, or stop doing a certain thing, or wants to bail out and discontinue associating with a certain person or persons because it no longer suits their agenda.
My girlfriend of 3 years didn't like my new job, so she decided to bail out on our relationship and be a " Ship-jumper".
ship jumper syndrome
a person that leaves his bf/gf/so/partner for a new one, and then leaves that person for a new one. and leaves that person for a new one, etc.
Allen has ship jumper syndrome, he left Jessica for Jane and left Jane for Valerie. He's like a rat jumping off a ship he thinks is sinking.