The worst aspect of losing is that it tends to create pessimism. Pessimism traps traders in the past, destroy their present and robs them of the future. Should a trader feel bad about losses or not?
Losses are part of the business, and the amount you lose is probably one of the few things that can be controlled. They shouldn’t be feared, but to get to that point takes a lot of work and experience to know that losses aren’t that big of a deal if risk management is properly practiced.
If you ask me then I can share my situation, When I loss I feel that it was my mistake I should close that pairs on time, Sometime greediness become key of loss 
As Pipcrawler already said, they are part of the game, so accept them.
A loss does not necessarily mean you have made a “mistake” in terms of your trading plan or strategy. If after every loss you were to re-evaluate and make changes to your trading approach you would spend all your time going round in circles. At some point in time you have to agree with yourself that you have an optimal profit ratio and concentrate on the profitable trades to extract yet more profit - this will off-set your losses (and at the end of the day it’s more enjoyable to work on profitable trades rather than losing trades).
Totally agree with Jezzode.
I have seen many traders who started to think based on formula: stop-loss = mistake
And because of this stereotype many traders are throwing their potentially profitable trading system in to a bin.
If you had a trading plan BEFORE you opened your trade.
If Your plan includes the right money management and risk management -> Stop-loses are just “expenses” of this business.
One professional trader said to me once: for me “stop-loss” - is just a ticket for a roller-coaster ride 
I think a trader with a right mindset about forex will not be discouraged by losing a trade because forex is a trade where there is 100% possibility for loss .And so when a trader experience lose it should make the trader make room for more and improved strategies in order to make profit.
It is part of the game. Even Manchester United can lose to Wigan, why can’t a trade went out with losses?
A trader should have 0 emotion for losses and 0 emotion with profits,
A trader should take every loss as a learning experience. Sit down and analyze what went wrong and make sure you learn a lesson for the next trade. A loss displays quite a bit of information about the trader and the strategy.
Nice idea…I feel this has to do with the psychology of it all. We should first of all realize and accept that losses would definitely come as trade in forex.
Having such a reality in mind will help be calm and seek the best way to deal with the problem. What I always advice is to analyze the situation and see what went wrong…Then try to avoid such mistake next time.