Ok, I know this is 'mumsnet' and I'm a dad rather than a mum but I am after a female perspective on whether I am being unreasonable.
My wife has never been overly interested in sex with me - when we first stated going out it was maybe 3 times a week. We got maried witihn 2 years and even by then it had dropped to once a week. It's really been downhill from there (been married 10 year next year - two kids 5 & 2.5). For the last two years it has been at most once a month (me always initiating) - which I think technically is a sexless marriage (