How can I help my boyfriend not *** quickly?

My boyfriend and i have been having intercourse for about 2 months now, and he on average lasts between 5 to ten minutes, and has lasted at max 20-30 minutes. He divulged to me that this has only happened to him when he was very eager to get with someone, but we've been together for a year now, so he shouldn't be that eager anymore. He says his average time used to be an hour or so, and he has no reason to lie. His self esteem is going down since he's unable to satisfy me and i'm not sure what I can do to help him. I refuse to fake it. Help?