Having your own space that is NOT in the living room can certainly minimize a lot of friction about decorating, speaker size, subs, etc.
Even so, my wife has always been pretty supportive. About 3 years after we got married, we bought our first house. The living room was about 12x14. I bought a pair of Acoustat Monitor 4's and had them pulled out 4' from the wall. (for those of you not familiar - those are about 5' tall, 3.5' wide, and about a foot deep if you count the tube amps built into the base).
She just rolled her eyes and joked with our friends that the living room was decorated in 'early speaker.'
The trick is that they have to know going in that you're an audio head and things like this will happen over time.
Now that I have my own room, the living room system has been scaled back to a nice set of Snell bookshelves flanking the 55" Mits Diamond. She's happy, I'm happy, and both rooms sound and look good.
Bryan