When I was in my 20s, I started dating a girl I met at the dojo. We're getting married in April. So, yeah, this situation can work out pretty well.
Over the years, my girl has gone through different phases of training for various reasons (health issues, 60-hour work weeks, etc), but she was always active. Currently, she lifts 2 days a week, does 1-2 yoga classes a week (one is a "restorative yoga" class which isn't a workout-workout), and occasionally bikes in the AM before work or we'll walk the dog for an hour or so once a week.
If I had a partner who didn't exercise at all and/or didn't understand that it's an important part of my life (literally part of my career), I do believe it'd be a source of tension but like DoubleD was saying, it should be something that can be figured out if you both work on it. Compromise, as it relates to many things in a relationship, is crucial.
Unless you're an actual competitor, you don't need to workout 15 hours a week and be a fussy diva at restaurants. Actually, @The_Mighty_Stu has talked a lot about how, when he was competing, he led as normal a "real life" as possible and did what he could to not let the training/nutrition interfere at home or work.
And, @ActivitiesGuy, for some reason I thought you guys already got hitched. Congrats, man. Also congrats, @EmilyQ on the engagement. Missed that one before. Glad to hear it