Vorstag.
Lydia was lost to the Fort Sunguard glitch, and Cordy was feeling a bit melancholic about the whole ordeal. I mean, sure, Lydia wasn't the greatest companion in the world -- always a bit put upon, constantly getting in the way--, but she was a friend, and friends were not something Cordelia came by easily. Drowning her sorrows in Markarth, knowing she couldn't fend off the hoards she would be facing alone, she decided to hire Vorstag in Lydia's place. You know, just until she could hold her own.
His easy nature, happy willingness to carry anything and everything up to the maximum, and general reliability made him a fixture in her life. The store is open and profitable, despite the fact that the only time Vorstag has left Cordelia's side is when she sent him to stay with the children while she scouted a location for their new house, and he happily supplies a nice, hot, home cooked meal even in the dankest depths of Skyrim's most unpleasant Nordic tombs. He would give his life to see Cordelia safe, and more than once has meant the difference between survival and an early trip to Sovngarde.
I feel like I've had more characters than currently exist in my saves, but that's because I've started and dropped so many. Those that remain haven't existed long enough to warrant a relationship escalating to marriage, so he's the only spouse I've collected so far, but he's nestled himself securely in my affections.
I'm entertaining the idea of Farkas for one of my Barenziahs, but if his negative attitude toward marrying another werewolf isn't a glitch, that could pose some narrative issues.