please tell me why Collin and Jenna separate and why she hate him that much she detto to him "i don't hate people that i don't care about" because i didn't watch the episode :....(

when jenna and Collin went to a club his ex was there and they started making out with each other then tried to have a 3 some. also she found out Collin never thought it was a relationship and he had been sleeping with his ex the whole time him and jenna were together.