Couple more thoughts for you:
-Yes e-mail him, nothing that the boss shouldn’t see but a note that his kissing you on your forehead this morning is still making you smile sort of thing.
-Ask him out. Take him out on a date, a real live datey-date with dinner & a movie or whatnot. Schedule it a head of time. “Sweetie, I was thinking I wanted to see that new Jodie Foster thing on Saturday, want to make it a date?” Dress up and be on a date with him.
-Schedule middle of the week wild sex nights. (Or at least very intimate, stress free nights. No bringing work home, no computer playing, just the two of you.) Again talk to him about how you want to spend Wednesday night with him and you want it to be special. Every week. Leave notes in his pocket/briefcase/lunch about what you want to do to him when he gets home. (These don’t have to be for public consumption.)
I’d avoid a “BIG TALK” unless you want to make him withdraw more and go on defensive. Decide what you want from him and figure out what you can do to make it happen. Telling him/Nagging him/having a big, serious talk won’t get you more cuddles, it will bring the problem to his attention but he’ll also feel threatened.
Give him affection, talk to him about his day, ask him if he’s worried about anything, ask him for what you want from him. (My SO will do things like stand in doorways until I give up my “Must Do Work Now” stress out attitude and give him a hug. Its not that I’m not an affection person or deeply in love with him, I’m just currently an over focused stress ball. He sees that and instead of getting riled that I’m not giving him enough hugs and cuddles, he just asks me for them. I grumble, I give him a hug, I relax, I feel better, he walks off smiling, I get back to work.)
Ask him to get off the comp for a movie night, or a kinky sex in the living room night, whatever.
If he remains uniterested in real life, consider having him see a doctor for depression…often depression can be seen in people who lose track of what they used to enjoy and they just kind of sink away into funk. It’s treatable and nothing horribly wrong with them, just something to track and get around.
after all of this, if he says he’s not interested in being with you and either depression is ruled out or he won’t see a doctor, then you can start worrying about leaving him etc. Until you talk to him you don’t know what’s going on in there and he doesn’t know you aren’t happy with the status quo.