I actually have a habit to masturbate. I m feeling weak during sex. What should I do?

May need to see Dr. Masturbation should be harmless to the body as long as he or she does not use too much force or friction on his or her genitals. One should realize that the body has essentially the same response to masturbation as to "sex for the purpose of reproduction". Masturbating fewer times a week, and not on the days one has sex, may solve the problem. If still having "weakness", see the doctor for help!
Grip. If a young man becomes accustomed to a hard grip while masturbating, he may be unaccustomed to the different, more subtle sensations during intercourse. I am wondering if this is what you are describing. Talk openly with your partner and try to figure out what makes each other happy, and things should solve themselves and strengthen your relationship.