He might get physically tired making love with u and so he may prefer masturbation.
Its the same with my husband also. He masturbates at least 3 times a week.He frankly admitted that he feels good masturbating because it doesn't involve much physical work.
All my husband likes is to watch movies, to play video games and go for window shopping.
I am also sailing in the same boat as u. Life *****.
does he eat vitamins everyday, and healthy?? another would be coffee, or energy drinks can wipe a persons energy out. maybe plan a day or night once or twice a month to spend just the two of you. . . go out and have fun, or stay in and have a romantic dinner. He could be having problems too, so ask him to sit down to talk to you! communication is key, and worse comes to worse, if you don't feel satisfied... move on. But try everything with the spicy foods, or extemporaneousness... If he works a lot, he needs to take a day to relax, and you can schedule something to do relaxing together (like a massage or hot tub)
You two are much too young to give up on sexual relations at this point. You both should sit down and have a heart-to-heart talk with you expressing your feelings in a non-threatening, tactful way. Hopefully, he will present some ideas from his side to help explain his lack of sexual interest. You should urge him to get in to see a doctor for a health checkup, if nothing obvious comes out of your talking things out. If it's a mystery to him also, a doctor might find something medically out of sorts, but from my point of view, it's odd that he could go this long without sex, unless he's getting satisfied through masturbation or . . . ? If I may be frank, trying to solve this, another angle would be for you to get a little aggressive and when he is in that cuddling, hugging, and kissing mood you mentioned (or even if he's not), unbuckle his belt, unzip his fly, and give him an unhurried hand job or b*l*o*w*j*o*b. Some men secretly want to be "attacked" in this fashion, but would never admit to it.
Make him eat carbohydrates and spicy food a lot. Appear more appealing in front of him. Make sure he does not masturbate. Remove all oils near his vicinity, make it tough for him to access other entertainment media like TV, internet, other girls if any.