I used to take my ring off when I play. Not that it necessarily made it harder to play, but with certain chords or fretting angles it would sometimes make a knock or clacking noise when it hit the side/back of the neck. I don't know that it even put any marks, but it was still annoying...especially on acoustic.
Really I guess it did make playing slightly harder, being that I would put effort into not letting it impact the neck, which would have an impact on the efficiency and comfort of hand positions.
But actually my ring is currently in need of repair (not indicative of the marriage mind you), so I haven't worn it at all for several months. My wife doesn't care, and there's other priorities for now.