Mass effect 3 romance

I just played through mass effect 1 and 2.. started on number 3.

I romanced Ashley in one and stayed celibate in 3.. and now I am at the dlc party.. and she is chatting up james.. I don't want to be with her anymore. But the only solution for me is to either play ME3 from scratch to get liara och to play ME2 all over again to even have a chance with anyone else..

So my question to you is "Is it your purpouse to make my character hate the only person he tried to have a relationship with?" because it certainly seems like it since all my actions in 2 and a half game has been to support and build my relationship with the character Ashley and you, with only one dlc, destroys that..