Spinning, I'm so sorry for you. I've been there and, as I've over shared many times, long-term ttc ruined our sex life. It is terrible for the men to have to perform on demand and yet we are desperate..desperate for the bloody sperm. I don't know what the answer is for you. We now do artificial insemination, as you know, which is just brilliant in terms of taking the pressure off and getting loads and loads of sperm in situ before, during and after ovulation. I really feel it is the perfect solution for us. I know, however, it isn't for everyone.
Communication is key: he has to step up and have sex with you at the right time if you are to have a chance of conceiving; He has to get his head around the fact that this is no longer the free and easy sexy sex you were perhaps having before TTC became more desperate and pressured. You have to accept he is not willing/able to produce the goods day after day over a high-pressure fertile window. There is simply no need for SMEP if you know when you ovulate.
Can you compromise and, say, DTD on ov (O), O-1 & O-3? Or summat similar? Remember that study that concluded most conceptions take place on the day before ov. Of course, this dictates that we know exactly the date of ovulation which, from the evidence on this thread, is easier said than done 