I would say, despite how embarrassing, awkward and hurtful it will be, to have a talk with him and come clean.

However, if you really just cannot bring yourself to do that, then stop faking gradually. Hopefully he will notice that you aren't having fun "anymore" and ask what is up. Then maybe you can tell him that he has to try harder.

Protect your heart until you find someone who can do it better than you.

Do NOT admit you've been faking it. Like the above poster said, stop faking them gradually. Next time it's not working for you, suggest a new position or something. If he asks why it doesn't work anymore, say "I don't know, I guess I just need something a little different." The key is communication.

I disagree with the others. I think you need to tell him it's a problem and you are not enjoying your sex life because he doesn't last long enough. Stop faking it, it is not helping him or you, and it is probably seriously eroding your intimacy, not to mention making for a terrible sex life and incompetent partner. Communication is so important in a relationship. As for the premature ejaculation here are some tips: Use a condom every time if you are not already. You can buy Trojan condoms that have a numbing cream on the inside of them that will desensitive him at the drugstore.
You can also just buy the cream on its own at sex shops, but you will have to use a condom with it, because you don't want your parts to go numb as well. Do not give him very much if any foreplay. Make him focus on you. Get him to make you orgasm through foreplay first at least once, before you even have intercourse. Make it all about you. Get him to perfect his oral sex technique and learn ways to stimulate you that do not include intercourse. Get him to use toys, clit vibraters like a silver bullet or a rabbit vibrater on you. Do not allow him to pressure you into sex until after you have orgasmed! During sex, have it with you on top. Go slow! Change positions often, because this will prolong his orgasm. You can also pull his testicles away from him body to prevent him from orgasming. (Right before men come, they rise up). Or, squeeze the base of his penis. There are books you can buy about this problem. But basically, you have to prioritize your own pleasure here. If he is unwilling to listen to or do any of these things, then find a new partner who makes your pleasure his priority and does not have this problem. Because it is a problem and one that is not going to go away unless things change, and you make him aware of the problem. If he still is too fast, then take your vibrater and masturbate in front of him until you come, or go in the bathroom and do it. He will get the picture that he is not doing his job. Don't be worried about offending his ego, because really, he is not worried about pleasing you so why should you be so concerned!? It will not change unless you two communicate about this issue. Good luck to you and I hope this helps.