I will keep this short, yes, lots of time for me, why think hes cheating?
Good Luck
O yes, no worries!! Even I am that way sometimes with my totally hot and awesome girlfriend and we've been together a year. Lots of factors contribute - maybe I'm tired that day and don't have the energy or vice versa, sometimes she's tired and not that into it other than moaning and groaning. Depending on the length of your sex life overall, such as myself for example, it just takes more than a woman lying back and letting me "do what I need to do" (which I hate BTW). I want her to be into it so don't worry at all! :-)
Maybe when he takes a long time to *** he is enjoying sex so much he doesn't want it to end. Encourage him. Do you masturbate each other? if not try this. If he's watching porn maybe you should try different positions. Good luck
If he normally ejacualates with no problem then he has to be doing something to prevent it from happening sometimes. He may not be necessarily cheating on you but he could be secretly looking at porn or masturbated to porn recently. Do you have something against him masturbating or looking at porn? If yes, then he may be hiding this from you. This is all just speculation, not necessarily the reason...