I have premature ejaculations. even my gf has begun to complain now cause of which i run away from sex now. i avoid her and losing interest in sex. pl?

At your age this: is likely more about the relationship dynamics in general and anxiety, specifically. Try non-demand sensual pleasuring (a la Master's and Johnson) and some relaxation (massage) without sexual expectation. Try pleasuring your partner in non-intercourse ways until she has some satisfaction, and then think about intercourse. Take the pressure off, talk about it, and see a sex therapist PRN.