How does one deal with disappointment, really? We face trials and tribulations on daily basis and everyday saw pockets of joy and even disappointment, I suppose. Certain disappointment are easier to overcome than others. For instance, you go for lunch and realised that your the stall has run out of your favourite plate of noodle - that is easier to deal with than say, building your ambition and putting in effort in something only to realise that you are rejected then that is a huge blow to your ego!
When things don't go our way--whether we're talking about election results, a job interview, a proposal at work, or a relationship--we naturally feel disappointed. We had hoped for the best, even expected the best and this apparent failure hits us pretty hard. So, the first step is to feel the emotion. Go ahead. Mad? Frustrated? Depressed? It's okay to allow yourself to feel it. You can commiserate with others or wallow alone--it's your choice. In my own experience of disappointment, I would wallow in anger first - that seems to be my coping mechanism. I just did today - I was down right disappointed with a proposal that was not accepted.
Then I would 'lick the wound' of disappointment by talking to people. Having said that, one should also know when to move on after the "would licking" stage is over.
I suppose that is where one has to be more rational and be "mindful". How? Take one giant step back. (I have not reached that yet - maybe will in a few days). I would have to step away from the swirl of thoughts and emotions and simply look at the issue in a sort of interested bystander way. It's as though you have a clipboard and you're taking note of your response: physically, emotionally.
I will pull myself together to move on - I have always done so. Life after all, is a journey. Certain parts of the journey would be smoother than others but if we keep our mind on the end, I suppose, it is easier to take on the rougher phases of the journey.