This whole situation reminds me of this comedy sketch on. The confusion in this comedy scene is in the two different languages been spoken about the bride's beauty. The same split is taking place in your conversation with your wife.

The question "Am I sexy?" in a purely logical sense, can be understood as: "Do I rate highly on an absolute scale of sexiness? If you plot me on a sexiness scale against all the other people on earth, do I rank highly?" If your wife isn't working as a professional model, and you aren't the envy of every man in your town, then it might be you feel unable to say yes. Whenever you are asked, you find yourself making an effort to lie. It feels a bit false and wrong. One day you aren't able to make the effort because you're sick of it. You say what you really think and all hell breaks loose. And yet - your wife isn't Helen of Troy! There's no secret here! Why are you being crucified for speaking a truth everyone knows?

The thing is, "Am I in the upper percentile of sexy people" probably wasn't the question she was asking. What she was really asking was, "Do you value me? Am I worth loving?"

Clearly you do like her. You love her in the bedroom so she must be doing something right. And you love her out of it, too. Unless you are lying to us, she must be very special to you. So say that to her with confidence and passion. Like the best man in the speech, no-one ever expected you to say something blatantly untrue. But we all need to be told by the people around us that we are worth something - that's what your words are supposed to signal, and the kind of support that husbands and wives are supposed to give each other.

There is an outside chance that your wife has crippling self-esteem issues and she is leaning on you too heavily to fill a gap that nothing can fill. In that case, she needs to learn to appreciate herself, a problem that goes beyond you and what you do. You shouldn't be under pressure over a problem of that scale.

But in the first instance, try to explain to her why you think she is special. You may find that once you get that across, things get better.