@FelineFan, I totally get where you are coming from. I feel similar with my DW, have been together 20+ years, have three amazing children, but the last few years possibly as much as 10 years, things have ground to a halt really.
I have been on antidepressants, due to work, for the last two years, and can affect me, which makes me withdrawn but before then, wasn't that which slowed things.
A few years ago during a conversation, she said she didn't fancy me anymore as she didn't think like that after we got married, which was a shock to me, always fancied her and more so after children, as I feel her body is more natural now than before, slightly underweight before, but now about size 12, but sexy as hell to me.
She always said she wanted someone 6ft, blue eyed blonde, I am 5'10", dark haired and brown eyes, and a few years ago, would have been about 8 or 9, I overheard her say to a neighbour as he was approaching her, don't as is at the window, I have was doing dishes with the window open, and I can lip read to some extent. When she came back inside, she came straight to me and was looking very worried, when I confronted her, she said that conversation didn't happen and had no clue what I was talking about, and had denied it after as well. I also said to the neighbour in question to leave my wife alone and stop sniffing round her, he didn't deny a thing, just said ok and has since moved. But slowly although she does say she loves me, usually in response to me saying it, we very rarely have sex, maybe once a month, she tends to go for HJ alot of the time, used to be daily sex and even two or three times a day/night. She is a housewife, I do some chores and help out and cook sometimes, I also work around 50 hours a week and am the only wage between us, but I have never limited her spending, joint account, no financial issues, mortgage will be gone soon, no credit cards, debts etc, so no worries there.
Just don't understand, and never get any answers from her, although have had the chance for an affair, not done it but can see why some would. Have thought about separating but feels too drastic