This "lack of validation" is actually an issue in my marriage. I've also refered to it as lack of attention, and lack of passion. My wife can also be critical at times, but she can also be indifferent, sulking, and depressed. It often gets to the point where I, too, don't want tio brin g the issue up, because it only causes grief, and it does not cause change.
Because of this lack of validation/attention/intimacy/passion in my marriage, I've been horribly tempted to have an affair or two. I haven't yet, because it would destroy my family. But there have been times when I just have to have SOMEONE validate me for me! I realized earlier today that is one of the main reasons why I flirt--it's a way to feel attractive to a member of the opposite sex without having to commit adultery! People cannot live without some minimum level of validation/attention/intimacy/passion, and that minimum level is (but of course) different for everybody.
Please don't take this as a criticism of YOU! I don't know all the details involved, of course. But I do see similarities to MY situation, and I am commenting on that.
If my explanation helps you, then great, but please don't feel offended (that is not my intent).