Going on about 5 years now. One of my best friend's is an Auburn guy. Our group of friends, about 7-10 of us over his house every Saturday, have adopted Auburn as a secondary rooting interest for College FB.
My heart is still with the Terps... but dammit if I haven't had a ton of fun the past few years rooting on the Tigers.
That's awesome. I don't really have a back-story to my love of Tennessee. Like you, I started following the Vols when they were just coming out of their prime (after Kiffin left). I followed lightly until Dooley's final year, when I followed a lot more closely. They started off so strong that year, ranked #23 in their game vs. Florida. But I really like Butch Jones, and watching them almost beat Georgia and then beat South Carolina was awesome.
I love "Rocky Top", and Neyland Stadium is one of the classics. Once I can afford to do it, I want to go to a Tennessee-Florida game in Neyland. I'm tentatively saying 3 years from now, when they'll be in Knoxville. Like you, I love the Terps. And the Big Ten is an awesome college football conference. But there's just no matching the intensity and level of play in the SEC.