Bran didn't get together with Jane until after Will was gone. It felt like a betrayal, somehow, which is silly, because he and Will were only friends. But for some reason, he felt like it shouldn't happen while Will was around.
In the aftermath, everyone was broken. It might have helped if they'd found a body. As things stand, some part of Bran is still convinced that Will isn't really dead. That's why it took him so long to ask Jenny out - because he always half-believed that Will was going to come back.
He still does, in a way. But he no longer thinks Will would mind his "disloyalty". He thinks that wherever he is, he knows. And he's happy.