I really wanted them to have an amicable, mature breakup where they realized their relationship wasn’t going to work for all the reasons it didn’t work in canon, but stayed friends. They could have long phone conversations about life, work, and monsters, and Dean could occasionally drop by and be Ben’s weird-but-awesome pseudo-uncle while Dean and Lisa hang out and watch movies and chat about their boyfriends. She would be someone who could talk about the hunting world without actually being part of it, a nice grey area between hunter and naïve bystander. And I really do like them together—she was there for him when no one else was, and he tried so hard to get it right even though he kind of failed. Without the complication of romance, they could be great friends, and really good for each other.
And then I remembered that I’m watching Supernatural.