Firstly I am sorry I realise it just came across that I think you are doing something wrong. Not at all. (although I still stand by my comments about splitting or therapy being better options than cheating)
I think the reason I brought up the 50/50 thing is because, like yourself, this has happened to me twice. (Been on the receiving end of sexual rejection from partners) I found out long after splitting from one of them that they closed up and pulled away from me because they felt like I wasnt giving 50/50. I have a chronic illness and mental health issues I know I am hard work. At the time however, to save hurting my feelings, instead of communicating with me that he resented me, he just closed up and stopped wanting sex and pretended everything was fine, he was just "Tired"
I just find people are always looking for this balance, and when it goes out of whack, wether real or imaginary, people start resenting. I see it all the time in the relationships I have had, and my friends, and I am guilty of it too. (and this thread is about it) I know I cant give as much physically because of being ill but I try to make up for it with organising and all that stuff. I see it everywhere though. Before I got with my current partner I dated a guy who finished with me after 6 months by giving me a pros and cons list about why he couldnt be with me. Examples included My kids. (The extra work I imagine) my illness (The extra work for him I imagine again) and not being able to do as many things he enjoyed because I needed extra support and couldnt work therefore he would miss out on a lot of luxuries. I mean that guy was clearly an arse. (Because he knew all that about me from the beginning but still slept with me for 6 months while he came to this conclusion) but in general I think humans by nature are quite selfish creatures. I also think if someone is allowed to be selfish, gets away with it I mean, they will take it for granted and want more. if you are doing much more than 50% in your relationship and still being told to go and find someone else because you want some love/affection/sex then clearly she is taking advantage of firstly your good nature and secondly I guess probably knowing you cant or wont leave anyway. All I was asking is that you find out if she feels you are giving 50/50 (Remember...subjective) You might be busting your ass doing all this for her and she might be taking it for granted and thinking hmmm he never hugs me anymore (or something you might not even be aware of) even though you are making a lot of practical effort (housework, work, cooking) Does she feel something else is missing? Does that make any sense? I am not saying you are not trying, just that in her head it might be something you hadnt even realised. Women are more emotional. and strange and I know myself that even though my ex did much more of the work than me, I felt resentful that he wasnt giving me as much love. I dont know if I am making sense or not but I am trying to say we are all complicated. The mars venus thing lol
All I am trying to do is help give you an insight into the mind of a female who has been in the same situation but also been in the opposite situation of being pestered when not in the mood. I wasnt in the mood because, well you know how some women almost use sex as a payment? (do the hoovering and I might give you a blowjob) well the opposite also applies. I have sometimes been in a situation where I feel like work is being done specifically to get into my good books. With sulking happening if sex doesn't happen. That sucks too. I dont want to be a payment for good behaviour, and I definitely do not want anyone to think they have a "right" to getting sex with me because they made some kind of effort. It is almost a running joke to get into the missus good books and you might get lucky. Its kind of icky though and it put me right off. Both sexes are guilty of that though.
I am not saying you do any of that, just rambling about my own rubbish to see if it helps in any way, prob not, because I have no answers and I couldnt work out my problems lol. I am sorry. I just hope it works out somehow for you because I have been there and it is not nice. In the end we did try couple counselling but it was too little too late for us. Too much resentments on both sides.