I think it's sometimes possibly disassociating with the problem and blaming someone else as a way to feel better.
For example, you know you have some bills coming up that you can't afford, and that bass/amp hasn't been collecting dust for months but you like the look of it. You don't really want to sell it, so she made you do it !
Personally, my GAS wouldn't know any ends, there's always something else I'd want. I do quite well, the missus will always buy me anything easy to get hold of or cheap (pickguard, strings etc) without asking.
When it comes to basses - I generally try to upgrade via trading rather than buying out right. I swapped a Yamaha BB614 for a Fender Jazz, and an Ibanez Musician for my Stingray, so i'm quite happy with that.