You should to stop masturbating as excess of every thing is bad.
Your body has become used/addicted to the act of instant & self gratification.
That is not something you can easily achieve with a partner.
You need to retrain your brain to be stimulated & gratified with a partner.
In order to do that you need to stop masturbating or limit your masturbation
Try that for a week and see if your sex with your life improves. also try anal squeezing exercise for two to three months .Disclaimer