He started going downhill within a chapter or so of her showing up and didn't get interesting again to LoC, but after she gets captured by the Shaido he gets boring again with the 100% obsessive focus on her. Frankly, out of the 10 principal love interests of our taveren trio - Egwene, Elayne, Min, Aviendha, and Lanfear for Rand, Faile and Berelain for Perrin, Tuon, the Tylin and that Aiel chick for Mat - the only ones that I feel added any depth to the story were Min, Lanfear as Selene and her book 4 aspect, and Mat's Aiel gal.

Actually pretty much every romantic relationship developed in the series screwed up the characters involved and made them more irritating - except Thom/Morraine, which was almost entirely off screen, and Nyneave/Lan, maybe just because whenever Nyneave was being irritating about Lan she was near one of the other girls who was being more irritating. I had been wishing some of the enormous volume devoted to the Last Battles would have explored Demandred's relationship with his Sharan chick but I'm actually glad in retrospect it wasn't because it probably would have ruined it.