How to stop faking it

So I've been faking orgasms with my partner for nearly a year now and despite having to do that (don't want to upset him as he's very proud and would be insanely jealous as I could cum via sex with my ex) the sex is genuinely amazing, best sex I've ever had. Better than with my ex where I would cum 5 times in a normal session. What I need help with is how to phase this out, I feel I will need a sort of narrative as telling him the truth is not an option. I've been lying to him to save his feelings but it's still lying. I want to be able to say that I'm struggling to orgasm and I want help with how to phase it out or what to say?