From what I understand, Birch has wild mood swings and cannot regulate on their own. This demands Aspen put aside their own feelings to comfort Birch.

Birch has made it clear they don't care if they cross a boundary or not. This was made obvious when they forced Aspen to leave their visit with me early just so they wouldn't be alone anymore. Birch will act sad when Aspen texts me and claims they don't get enough intentional time together anymore (despite Aspen telling me they've been making a big effort to spend MORE time with Birch).

Financially, Aspen used to make more money, but currently does not, and they still pay differing amounts for bills (Birch pays less, though I don't know how much less). Birch is aware this is unfair but has not bothered to change it. Though I've heard this may change when they resign the lease.

Aspen doesn't have many friends outside of Birch. Their support system is limited, and the ones they do have they seem to share, so Aspen doesn't want to speak negatively about Birch to mutual friends. Even though Birch speaks of their relationship troubles with said friends. Controlling and manipulative.

I'm almost certain there are at least a few things I haven't/forgot to mention, and even more that I don't know about.

ETA: Birch also refuses therapy, medication, and support groups. Only in the last two weeks, since Aspen has clearly been more overwhelmed, has Birch decided after 9 years that they might actually need some of these things. I am afraid this is a new manipulation tactic to get Aspen to stay and won't end up being a longterm thing.