Did you tell her when she was opening her account that you also wanted to open up one? Like... honestly, I would never suspect that someone else wanted to open up an account at the same time as me, and with the same company as me. I view finances as something very personal and not a joint-thing unless it was a very commited relationship (as in, married or common-law or at least living-with-each-other-for-a-long-time). Then again... I've had a bank account since I was 5 and can't imagine only just opening one up when an adult/teen (I don't know how old you are, sorry).

She's not really making assumptions though. Unless you've told her "I need help with my finances and setting things up" then she is responding as she would to anyone else - unfortunately needing help with setting up finances is in the minority, and she has no way to know that you're in that minority unless you have told her and asked for her help before she did her own.

I don't see why you can't go to the bank and say "I'd like to deposit this money into my account".... that's what banks are for. I also do not understand why you couldn't open up your account in a similar way to her. What does doing it at a later date have to do with anything? It confuses me.

What does your girlfriend already do to help you with not thinking for yourself? Like.. I suppose I also do not understand your difficulties as you haven't really explained them - aside from saying that you can't think for yourself.

ETA: I just remembered that she's your fiancee,.