It's tricky.....I've been dating the same girl for years...and overall she's pretty cool.
Except...she seems to react when a new guitar shows up, giving me a hard time etc...but never takes into account when I sell a guitar for way more than purchased etc... I guess
those transactions don't count.
I'm pretty honest with her though. Since we're not married--and not living together, I just throw it out there that "I am how I am....I'll buy what I want (and can afford)....take me or leave me! " If my hobbies are any reason for her to pick the second option....then I guess it shouldn't be anyways!
-C
ps....that said, I have certainly "slowly reveal" guitars if I've bought a few at one time, else she thinks I've spent my life savings on guitars.

This includes having them shipped to friend's places etc. What a strange game, eh?