It seems that he has erectile dysfunction problem or premature ejaculation problem. If you get sexually excited before the intercourse, and he keeps his penis erect for some time you can reach climax. For getting excited, you may do female deer exercise or encircle clitoris with your finger. Google female deer exercise. you may indirectly hint to google and find out few exercises to strengthen his sexual stamina. Edging, kegel, micro-cosmic orbit circulation, Sat kriya etc are good exercise.
Consider first intercourse as a trial one and do it again after half an hour. He may last longer in the second intercourse.Do not hurry up second one. Wait patiently for his excitement.It is not your fault that he is not able to perform.
Touch yourself while doing it