Again, Ziam. My theory is that they were dating until Liam met Niall, and Niam became real. This broke Zayn's heart and he's had to live with it until he finally he quit the band. He couldn't stand Niam.
Zayn was crying and Liam ran over to comfort him ♥ (GIF) AWWWWWWWWWW :*) Liam's run tho, and look how louis (wait that may be Harry i can't tell) like grabs him trying to take him from liam and then suddenly Niall pops out of nowhere.