Ant is married - so I doubt it. There are lots of rumours about the little un though, but no proof.
A&D are on holiday in America at the moment, and they have left the wife (singular) at home. I guess she is too busy working. Follow them on twitter.
If A&D are indeed a couple, why did he marry Lisa? He seems too down to earth to have a beard.
I am not suggesting Ant and Dec are not straight BUT, just imagine Ant and Dec are together as a couple and one has married for career reasons (probably not as they seem genuine but just go with me...)...
Do you think they'd get all those high-profile gigs on British television as an openly involved gay male couple? Would Cowbell look twice at them? Now for sure, I'd employ them, but I'm not the paranoid business suits sat in an office worrying about viewer ratings. Why draw attention to your hosts as being 'involved' (which would surely happen) when the focus should be on contestants?
If they were involved (theory only, folks) then the strategy has allowed them to become almost inseparable whilst flying under the radar. They are probably happy with their respective lives/partners, whatnot. I hope they are straight and happy with wives/gfs because the prospect of yet more closet cases in entertainment is depressing.