hi everyone !

I am a new user to this forum and as all of us here, I have a question. I`ve been with my girlfriend for more than 3 years now. i am 20y old and she is the second girl i had sex with. my problem is that i get easily excited, just by looking at her her body (in my view she is hot) and very often. usually we do not have a very long prelude and skip to the "action". my actual problem is that i go off after 2-3 minutes. i know that this is normal or that it might just be in my head but there is always room for better. has anyone else dealt with this problem ? the problem varies from time to time. sometimes intercourse can last up to 30 minutes and sometimes it takes less than a minute for me to finish. i also wish to mention that she never had an orgasm (event though i`m the second guy she had sex with). recently i discovered the kegel exercises and try to keep up with them and try to train. can someone give me an advice ?

p.s0 some may say that she deserves a better man or that i should search a new girl but we are great together and wish to remain like this, for now. please do not mock nor joke on this subject. thank you !