I've used Linux full time for three years. My wife "clung" to XP as if she'd jumped off the Titanic and XP was a heated life raft. The turning point came when the anti virus software (Kaspersky) was driving her nuts with it's intrusive permission seeking popups.
Now I've always used KDE, why? It in my opinion looks "nicer" than Gnome. After using PCLinuxOS for two years then migrating to Mandriva with KDE4 I finally convinced her to change to Mandriva. Now I've found as Mandy went from 4.0 to 4.3 things on my PC were gradually slowing down and I was getting the "this worked in Windows" crap from my wife. Now as a sideline she had Ubuntu XFCE in her laptop (used for web when in bed at night) and she never complained about it but the laptop started playing up. I was not sure if it was hardware or software so I decided to change disto to see.
Now I've always hated Ubuntu because it's as ugly as a "basket full of Monkey butts" but I'd always has a soft spot for Mint. That came from when I was a newbie and Mint had the audio / video codecs installed. I installed Mint on her Dell and unfortunatley it did turn out to be the laptop with the issue but she never complained about Mint. Some simple maths here: number of compliants versus OS = WSR (Wife Satisfaction Rating)
I installed Mint on her desktop two weeks ago and she loves it (what that really means is she can't complain about it) One point for Mint. (I also changed to Mint)
Feel free to post your partner stories here.