Short time ejaculation. Please suggest.

Hello, I am 26 years old. I am going to marry my gf within 3 months, we have 5 years of relation. We had sex 6 to 7 times. Now the problem is, in each nd every times when we had sex, after meet her and after some kissing when I was ready to do the main thing like just trying to insert penis into vagina, I had ejaculated after 1 or 2 stroke means enjoy is finished before starting. But after 1 or 2 hour when we had further sex then it was okay. so, the problem was in 1st attempt but it happens last 7 times when we had sex. the gap of 7 times sex is 1 or 2 months. But after 1 month of our sex when we planned another day for sex, that time also same happens, I met her, kiss her and when ready to do, I had ejaculated after 1 stroke and that same day after 1 hour then okay. It happens every time. Please suggest.