Why cant I climax during sex?

Since you were on top and got tired after an hour why didn't you ask your partner to switch and get on top. Many women love to top a guy and hump him up and down and sideways. It stimulates her and him at the same time. Maybe you can climax if she does that. As to your foreskin, you may want to use KY gel to lubricate it so the tip won't be sore or irritated. There would be no need for a condom except for protection from pregnancy.