I lost my girlfriend because I used to really quick when we have sex the first round I in less than a minute but the good thing is I used to be ready n hard again within 5 minutes I used to satisfy her the second round I use to last forever but the first round I never lasted more than a min my girlfriend never complained because she knows I can do second round third forth but the other day we were having sex I ejaculated quick first she got a bit upset she didn't let me go for second and she broke up:( I feel so useless she left me because I came quick:( I don't know what to do I love her so much:( I need some help please is it my fault really? 

No, it's not your fault, and it might not be the reason she left (there's usually many more than one). A woman who loves you will talk about what she wants in bed, and give it time to work in a way that's good for both of you, and not consider it a major part of the relationship anyway.

While I agree that it isn't your fault. I was like that for a while, I would start, get hard, stick it in, and BAMM! (Honest that was the sound effect too!). It will pass and you just need to train yourself out of it.

Honestly you just need more foreplay and less grinding on your part. Get yourself hard sure, but make sure she gets off or gets close enough before you penetrate. Maybe the next batch of condoms could be the sensation reducing ones. Just make sure you put them on the right way.

I agree with the earlier responses and especially with the likelihood that there is more to this story. And if there is not more to the story ( that is to say- that's the only reason she left), it is probably best for both of you, that she did end it.