I have the opposite problem--we talk about everything BUT the past. But I am really impressed that you have noticed this pattern and are interested in changing it.

I do think this is the kind of thing family therapy might be able to help. It sounds like you even have a way to approach it. You could explain that you've noticed this pattern and want to connect on more things than the past, and thought a counselor might be able to help you two find a different way to connect. I think you're right that going into this with you might help her try doing some individual work, too. It's clear you care about her and your relationship.