I don't think he'll think it's fair.
I have more annual leave than he does, and we both end up with about the same disposable income. He spends his, I don't spend much of mine so it's built up.
I've never been able to afford many holidays, but in the past with his ex they used to go on lots of expensive holidays. Not really relevant, but I feel he's had a lot of experiences I always wanted but missed out on, and now I can afford it, I would like to go myself. We can't afford to both do them (unless he saved all his money too, which he wouldn't want to do as he really enjoys what he does with it) we do go on one holiday a year together.
AIBU to book myself a dream trip? Would you feel resentful if you were him?