My girlfriend is satisfied, but I am having a really hard time. I don't get bored easily.

I use a condom, and even if I take it off and do it for over an hour, I can't ejaculate. It takes more than two hours to ejaculate, but I don't do it inside. When I try to pull out, I feel okay, but I don't do it unless I'm married. I do it outside after taking it off, but is there a treatment method? My girlfriend keeps wanting to continue, but what should I do? I'm struggling and have lost about 5 kg.