That question really depends on what you want out of the game. Do you want to increase your win rate in turn lowering theirs? Do you just want to get more comfortable with losing and learn to enjoy it more?
The best way to deal with it IMO is to focus on getting better, while keeping in mind that what you can't control is not worth getting upset over.
However, there's some key pieces of information you haven't mentioned for us to figure out how to help you get better. Which are, how much research do you put into getting mechanically better and politically better at the game? How far do you feel like you've grown as a player in terms of skill in the last two years? To know what would be most beneficial for you to focus on, we need to know where you are at in those particular skills vs where the winner might be at