I wonder if he‘s just feeling a bit lonely and the lounge is more cosy and probably carries your scent and makes him feel more secure? Could you maybe leave him something of yours, an old T shirt or similar? Does he start making a fuss at the same time every night which could point to something disturbing him?
My dog (6) has always slept in the hall but if the lounge door was accidently left open then that‘s where I‘d often find him in the morning and having now been allowed to do that, he‘s recently started creeping up the stairs once the lights are out and sleeping quietly in the corner of the bedroom.
Cockers are very much velcro dogs and will always prefer to be with their humans rather than be alone but understandably not everyone wants their dogs on the furniture, in the bed etc so if he really is unhappy in the kitchen/ utility, maybe you could use a baby gate to close off no go areas while allowing him a bit more freedom, ? Perhaps a gate rather than a shut door would prevent him feeling quite so cut off from you?
I‘ve made the mistake of being inconsistent and have allowed a good five year habit of sleeping downstairs to be broken in just a couple of nights and I could kick myself. If you really don’t want your dog to sleep in the lounge, then my advice is don‘t allow it even for one night, its very hard to go back.
Hope you find a solution!