My bf and I have been together for 4 years. While I doubt he'll ever get to the obsession-level that I am, he's definitely become a fan.
When we first started dating, he'd never even ridden a roller coaster. (Not that he was scared, the rest of his family just wasn't interested when he was growing up, so they never brought him to an amusement park) He went to Universal Studios once with his cousins when he was in his late-teens/early-20's, but that was before they had any coasters. So his exposure to theme parks was limited to that (He still pines for Back to the Future)
In 4 years I've gotten him on 80+ coasters around the northeast and mid-Atlantic, and we've made three trips to WDW. Two week-long trips during Food & Wine, and a long weekend during Gay Days. In the parks he mostly just allows me to lead him around, and he still gets things confused in his mind (he gets aspects of Haunted Mansion and Tower of Terror confused, doesn't remember which park things are in, etc) but he's definitely hooked.
He's an architect and enjoys plants and gardening, so he's always looking at how the parks are designed and landscaped. (One time he walked up to an archway that looked like stone at Saratoga Springs and knocked on it, and was a little dismayed to find that it wasn't real stone. This gave birth to the running joke "Don't touch the walls if you don't want to ruin the magic!")
He's also confused sometimes with how they build things, like the fact that they built the "core" of the Avatar FoP ride building and then they built the outer walls around it. I had to remind him that theme park design and construction requirements are often different than office buildings and lab spaces...
Just last night we were looking at screenshots of aerial footage of the Star Wars Land construction at Disneyland, and we were talking about the layout and the different buildings and what the various foundations might be for. Definitely hooked.
This year we're taking a year off from Disney and doing an "everything but Disney" trip to Orlando to spend some time at Universal, Sea World and Busch Gardens. (Though definitely with a few evenings at Disney Springs and a visit to Trader Sam's) Then in Fall 2018 we're planning a trip back to WDW with up to a dozen friends from college, many of which have been saying "I want to go to Disney with you to see what you see in it"...
-Rob