Moonpaws,
First off I'd like to say I know exactly what you and your boyfriend are going through. I'm sorry y'all are at this point, it is however common and beatable, there is hope!
Short answer followed by long story here. Meth desensitizes you after you build up a tolerance from going too hard too long. At this point you become so detached that real sex is less pleasurable then just stroking yourself. What's going through his mind right now is that it is easier for him to go solo in order to get more out of it- the high, the pleasure, the meth is trying to squeeze as much recycled dopamine from the brain as it can and it becomes a calculation borne of desperation. Maximizing the crumbs of pleasure with the inevitability of reaching the end of the body's limits to gain from the drug. It also alienates you from others and your partner and these thoughts whisper to you from your subconscious and conscious sides, they are easy to confuse for the voice from your own head. I digress lest I start talking about the meth-self.
As the posters before me stated so eloquently, he is addicted. There is no easy fix and it takes communication, love, and support. However the above gives you an insight as to what he is going through. It took me a few months to taper off with many hiccups of relapse in between. I am over a year sober but mainly because I'm also deployed and when I go on leave you can guess what I'll be doing. Anywho let me continue.
I learned to enjoy actual sex again with my wife again after those said few months of sobriety so it is possible. Having her as a support system helped me tremendously with seeing the value in the love and hope I possessed, and it was a factor in why I wanted to get sober again. Your boyfriend will be lucky to have you in that regard.
The big thing is he must have a conversation with himself and be ready to take a break for himself! Even if the only reason is selfish like sobering up just to get that good first hit again! It must not because of obligations or reasons of practicality and logic, otherwise this will push the need to use deeper into the psyche and it becomes his only refuge. Whatever it takes to get out of the woods and lift the fog, bribe and trick yourself if you have to, trust me it gets easier as you let in life's pleasures again. But have a goal that awaits you while you're in the slump and you can see yourself through to the light again.
I got that way several times, behaving in much the same way you boyfriend is now. The hardest part is admitting to yourself you have a problem, the next is resisting the withdrawal temptations to use while your body, mind, and soul recover- for however long you want to. Luckily my goal I knew I wanted was to do the drug and not let it do me. To return to the sensation of that first great rush. It is a fine line and too often you don't realize how tight she has her claws around you.
I'm sorry for the long post, I wanted to be thorough and let you know you're not alone. It can and will get better if you and him let it.
