Why soooo many planes???
After reading all these posts, man I'm one lucky guy.
First, if the girlfriend disagrees now, what will it be like later?
If you are not taking your last dollar for the hobby, and she doesn't get put on the back burner, theoretically, there should be no problems.
My wife supports my hobby big time, but she doesn't like coming to the field unless she knows a lot of people.
We have each our own money from our own income and this has worked perfectly.
Get her involved in some of the buying decision and she might understand better, but that's a long shot.