My girlfriend supports my collecting habit - she loves buying and reading books as much as I do. She also understands the fun in collecting special editions, various versions of the same title et cetera. But she would never spend as much on a single book as I would. She also does not know exactly how much I spent on my collection (actually - I don't, either). But as long as I pay for the books myself and I still have enough left to pay my part in our household, there is no problem (although she would probably like me to save more - she has about six times as much $$ in her savings account as I have!)