Man, this is bad, and i personally think this relationship is on borrowed time. I could not be in a sexless relationship, but thats just me, but tell me, if you're not having sex, to me, your not in "love". Heres simple, whats the difference between loving each other, and just being very close friends? Sex, right? I have friends, im not "in love" with them, but i do love them, you know...i a siblingy sort of way, how is this different? Your not having sex, which is my mind is the phsysical act of being in love (others are welcome to dismiss this as, this is on my own view point on "in love"...), this fizz has gone, so now, to all intents and perposes, your just two very good friends, who show light emotional connections, and happen to live together...i could say the same about friends that i've never had sex with at all....
Ok, solutions, i reckon this is tricky, very tricky, you might not even want to hear about it....So....the worst case scenario...move on? Stay friends, strike up a new love with somebody else. Sounds heartless in essense, but, your already being fair to her as you are, but....are you being fair to yourself? You deserve to be happy. It also sounds quite awful, that your masturbation sessions have to be kept on the low down, i think her self-esteem could be to blame, but really, is it fair that you have to carry the emotion burden for two people? Ironic that you masturbating, makes her guilty for knowing thats the only option of fulfilment you have available, which in turn, makes you feel guilty for making her feel guilty.....c'mon she's backing you into a corner and you're running out of choices.
I understand if you confirmed to stay with this woman, the breaking up is definately not an option, if thats what you have decided, which leaves, convincing her to become sexally active again (which is sounds as if all effort on that score has already been exhausted), or having sex with somebody else while staying emotionally in love with her (a very risky path...)
I think you need to sit down together and really dig into this problem, be firm but fair, dont try to force anything from her, but, do make sure that she knows down to a T, exactly how you feel. Tell her that you swore to defend your honour in marriage, but that untimately, the full picture of the relationship at present, does not meet your needs. I think from your post, you wont be keen on having sex with somebody else, which means, your commiting to unfulfilment with your current wife unless she changes her stance, then, unless you are prepared to move on, your going to be doomed to your once-every-six-months-no-foreplay-dull-as-hell sex session.
Its such a bad state of affairs, i really feel for you man, because i know i would hate, and couldn't personally, be in your situation. Its on you, but i only see a couple of choices (because you've already tried counselling). a)Move on and try to stay friends b) Stay emotionally involved and married, but have another sexual partner c) Do everything in your power to make her sexually active again, and make sure she is aware your marriage is at stake, and, encourage her to masturbate when you aren't there (you could even buy her some lingerie or a sex toy). I cannot, by principle, give you advice to encourage you to stop neededing sex, we have instincts and requirements which should not be hindered, in fact they should be encouraged, to me, a sex life is as important as eating and sleeping, therefore, it is against my every fibre, to tell you to stop needing sex, i just dont roll that way.....
So, its on you, are you going to commit and stay doomed, or change something....?