Smeeinit, Life has its ups and its downs. I am not being catastrophic, but even if in a year or so things should not work out for you, and your income levels drop, you might regret NOT celebrating your successes if you dont buy that watch.
I have been where you are now, on a high salary with a big multinational internet firm. I bought white gold and diamond necklaces and ear rings. I went on the holidays. I bought a DKNY watch, not because it was a classy label, not because it was expensive (compared to yours it wasnt), but I just LOVED the way it looks. The battery is off, and it needs sending to Italy costing £50, so I have to forget about it. After my "up" I have over the last few years since leaving my job and starting my own business with my dh had to learn to live on less and less and less.
At the moment I have a thread about having only £88 in my account, well, it is overdrawn by now, no money coming in in the foreseable future, I will just have to take things as they come, and feel sad for the items I cannot buy my kids such as a new winter duvet for my son. I am piling him high with blankets, it will have to do for now. My point is: I dont regret buying a few luxury items for myself when I could. I am glad to have experienced the up, and I have a lot to learn from "the down" yet.
Treat yourself!