Me and my fiancée have been together for about three years. We are still madly in love and everything is going well, except the sex. About a year-and-a-half ago, we started having sex less and it’s just decreased until the sex is now non-existent. He insists it’s nothing to do with me and he still tells me I’m beautiful and compliments me. I’ve tried talking to him so many times in so many different ways, but he just makes up different excuses all the time. He acknowledges that the sex has stopped and says he misses it, but then doesn’t do anything about it. I’ve tried coming onto him and he just turns me down. I don’t want to have to end the relationship, as I love him, we’re engaged and own a house together, but, how can I go on like this? Eventually it will take its toll and I’m starting to think about having sex with other men. I’d never cheat on him but the fact I’m thinking about it is bad enough.
LemonVibe 
Sex is never an easy topic with your partner, especially when you’re not saying good things about them.. Perhaps he should go and have everything checked out? I know that I had no sex drive because my body was not producing enough testosterone. I am now on a supplement which has helped a lot!
Tell him how you feel. Be blunt. Sometimes it’s what men need. Hopefully he will be open minded about it all.
You might find that he needs to actually have his bloods done. I found that I was tired alot, slightly moody and no sex drive. My doctor found that my body wasn’t producing enough/normal amount of testosterone. So I am currently on a supplement which has helped tremendously!
I would honestly let him know that this is a BIG problem. I mean you may have discussed it with him but since he doesn’t have the same sex drive, he isn’t really understanding how important this is to you. Im going through a similar situation now and i actually felt gross because he just seemed to want to get it over with. It hurts and it sucks. You are engaged and you are not yet married. While you may be madly in love, are you willing to continue to scarifice this aspect of your relationship forever? I mean, as these lovely posters before me have said, there may be something he needs to have checked that could assist with this issue. (Did you know that sleep apnea can cause a decrease in sex drive?) Either way, whether this gets addressed or they don’t, are you willing to stand beside him til death do you part?
Sure there is a possibility of a health reason and you should insist upon a check up by a doctor in that specific field. Since he hasn’t done that yet might mean that he is ashamed of it or not afraid of losing you, knowing your natural desires. But there are other possibilities. Perhaps he is having an affair with another woman and having sex with both of you might bother his conscious. Or perhaps he is gay and thinks of you as a wonderful friend and roommate and if he was to tell you the truth he knows it would hurt you too much.
First, go with him to the doctors appointment and be there to hear the diagnosis. If it is medical, you have a very tough decision that only you can make for yourself. You did not state your age. That would have been a key factor for advice for your situation.
If it is not medical, become your own private investigator. Start with phone records. If you don’t have the time, hire one.
If you don’t know the truth of the matter how can you come to the correct decision.
To thy own self, be true.