Grrr, experts! Reminds me of my exH.....

Whinging away about how things should be, never happy unless it's his idea grrr ggrr grrrr. When he would start like this I would just say - ok so how do you think it should be. O.k well that won't work - want to know why?
So once they can get off the whinging about it (if at all, some people just get hooked on complaining iykwim?), I'd explain - they actuality of the situation, what you are prepared to do to achieve it and finally, a clear statement from him about what it is HE will do to facilitate it as well as you. Then tell him to shut up or you won't do it at all.....

Yep - single for a reason!