As hard as we might try to avoid it, it does happen sometimes that we gamers fall in love with someone who has never heard of role playing games.
So what do you do?
You could always just go off and game with your regular group, and leave your significant other out of the loop. That works for some relationships, but for others is a bad sign. I'll assume that you want to work your SO into gaming in some fashion so you can share your hobby with him.
The key is to start slowly. You've had a long time to build up a lot of enthusiasm about role playing games. You can't spring all that energy onto someone all at once, and expect them to understand. Get them into gaming slowly, and let them develop their own enthusiasm.
Here are some tips for doing just that.
Try A Convention
This can be a trial by fire approach, but it worked well for me. A gaming convention is a wonderfully fun event, with lots of people dressed up and acting out their character's parts. You'll find live action role playing, table top role playing, every type of gaming you could imagine.
The enthusiasm all these strangers show for the hobby is a bit infectious, and can do for your SO what your own enthusiasm might not. The danger of this approach is that your SO might come to love gaming conventions so much that they'll have trouble role playing with just the two of you at home.
Try A Murder Mystery Party
Murder mystery parties are a form of socially acceptable role playing game. While your SO might look askance if you ask them to adventure with you to stop the evil necromancer from enslaving the village folk, they'll probably be okay with a murder mystery party.
The best sort are not the boxed sets, but a more freeform game. These are basically live action role playing games with simplified rules and require little intervention from a GM.
My favorite murder mystery party for a small group is Death on the Gambia, by Freeform Games. Nobody is what they seem, and there's a lot of intrigue going on.
Try Board Games
Many of the non-traditional board games that we role players love have RPG elements to them, and can serve as an introduction to the hobby.
One of my favorite quick games is Betrayal At House On The Hill.
Each of the players takes on the role of a character exploring a haunted house. The characters have stats, much like a simple role playing game. They explore the house, coming across items and events, and generally getting into trouble.
Eventually the haunting starts, and one of the characters turns traitor. There are 50 different haunting scenarios, so each time you play you have a different game. Unfortunately, this game was published in 2004, and can be difficult to find these days. Google typically still shows a couple of online stores carrying it, though.
All of these options can be used to introduce a non-gaming SO to gaming, in such a way that they don't run screaming from the room. Even so, you may find that they just don't take to your hobby the way you do.
And that's fine, too.