Suggest Treatment For Premature Ejaculation

hello doctor, i have an embarrassing problem which is killing me psychologically. i used to masturbate a lot when i was 17yrs but i stopped at the age 26 and i am now 30yrs. my problem is whenever i have sex i ejaculate prematurely. doctor formally it happens just at the point of entry but it has somehow improve now. now i can do like 3 stroke before i ejaculate. is there any treatment for my condition. please i just want to know what i can do resolve it because it is destroying my marriage. please i need your help to save my marriage. thank you.