While I always remember that I'm just a fanboy, I do see her point. So it boils down to whether I want to own a game just to own it, or whether I'm actually going to play it physically at a table. To that end, several of my most beloved games went on the chopping block recently - and for two major reasons: First, I'm not likely to actually play them physically - or in some cases, I've never played them physically. And on a related note, I'm an active gamer and not a collector.
To that end, it is after much hemming and hauling that I decided to get rid of most of my Swords & Wizardry Complete books. I'm keeping a physical core book, the screen, and Monstrosities - but everything else is going. The physicals I'm getting rid of I own all in PDF (except one or two), and am more likely to play with my OSR kin over Roll20 than at a table - so eletronic versions will certainly serve me as well as the physicals.
The huge realization is that parting from the physicals isn't some "disrespect" to the game's creators. Matt Finch and Frog God Games still had (and continue to have) a huge and positive impact on my career as a writer. Not physically owning certain books will not diminish that and the books I decided to keep will continue to aid me in design.
In addition to parting with my S&W Complete books, I also put up my OSRIC core. I purchased it and it immediately went on the shelf. I never even opened it. Others included my collection of the newer incarnation of World of Darkness and Changeling: The Lost, Astonishing Swordsmen & Sorcerers of Hyperborea, and my Beyond the Wall books. Am I doing a larger disservice by continually choosing to play other games over them and letting them linger on a shelf, or sending them to a home where they'll be valued either at a table or among a collector? I think, in the end, the former is the case.
In the end, our love of the game is not defined by how large a collection we own - though owning a large collection is pretty cool. Near every book we part with can be reacquired when the time comes. So, by recognizing that my collection is a fluid, changing thing, it becomes easier to part with these books and a comfort comes in the fact that they will reside with someone who values them as part of a collection and does not require the necessity of active use for ownership.
For me, in the end, it comes down to an old mantra spoken often when one must part with something that has been a source of affection and love in their lives: If you love something, let it go.