Is it possible to fix dent on AT gold bezel?

It's a spectacular watch so it's easy to understand your wife's disappointment. Frankly, dings like that are nearly impossible to avoid if the watch is worn with some frequency. I have a similar watch and it's very dear to me -- it was given as a gift by Mrs. Jones, and it's the watch which first infected me with the sickness we call collecting. After about seven years of ownership, I had accumulated a few small dings on the bezel, like the ones on your wife's watch. A few months ago it experienced a minor mechanical malfunction and I sent it to Omega for repair and regular servicing. It came back looking like new, as it had been lightly polished as part of the service. So I think going forward, I'm willing to live with some accumulated dings and dents, knowing that they can eventually be buffed away.

...and just to be clear regarding buffing and polishing...highly collectable vintage watches can be significantly devalued by polishing. Preservation of the original edges and bevels is way, way more important than having a shiny appearance 😀

One of the disadvantages of gold is its softness relative to steel, you'll get more swirls, scratches and dents just by that nature. It doesn't look that bad to my eyes, I'd just leave it as it will acquire more marks as it is worn.

@maconomist , I don't think Omega offers laser welding at this point, you would be better off finding a third party who is familiar with this process. And they would be a lot cheaper than an Omega provided service.