On the 'good' path, Jake takes almost ALL the blame. He even says as much several times, that he wasn't there. From the conversation at the park, to the driving to/from WUI. Even at the dinner date, he takes the blame. Never once tries to turn anything to her, it was all MC.
On the 'hate' path, the blame is written as almost exclusively Allie's fault. I've never done this path, just going off what other posters have said. That she was never around, she ignored him. Jake says most of the items, and Allie has a lot of ellipses.
So the conversation differences are sprinkled around quite heavily it seems.
I get that it was likely both somewhat at fault, but the dev/author seems to want the main responsibility to depend on the path you are taking.