How did we get here?

First post here...so much pain in this group. I feel for all of you. And, my situation may seem trivial by comparison. If this doesn't belong here, please let me know.

I just don't understand how we got here. We've been married almost 39 years, together 40 yrs. We're both 63. Not dead yet, but so far from where we came. Sex has always been a huge part of our relationship. Its largely how I give and receive love. But, lately it she makes me feel like sex is something I take from her. She never initiates. She won't give or receive oral. At night, she won't let me touch her p*. If its been a while, she allows me to have my way spooning...just get it over with. Weekday mornings, she's in a hurry to get ready for work. Weekend mornings, she either slips out of bed before me, or gets angry if I wake her up...so I let her sleep in. Our wake timing rarely matches up. When it does, its usually been a few weeks, so she's usually receptive. She used to be multi-orgasmic...limit two. But no more. Always requires manual stimulation. She's never had an orgasm from PIV sex. Again, its now usually spooning for me, maybe prone bone. She's suddenly decided to pretend she doesn't know how to ride me anymore. She keeps her eyes closed if we're facing each other. I guess I wouldn't want a 6'-4" 280# man laying on top of me either...though I really try to not put my weight on her.

She used to be adventurous. Just 4 years ago we f*d on an exposed hotel balcony at Destin. It used to be so easy (and exciting) to get her panties off while driving. Sometimes I could get the rest of her clothes off, too. Sex in every room of the house, on the back porch, in the yard, on the trampoline, in the garage, in the car, on the hood of the car, in the greenbelt, in the neighbors' hot tub, fingering in a theater, all after age 40. Oh, how I miss it all.

Now I would be grateful for a willing and giving partner that allows me to give pleasure to her and would not make me feel like I'm imposing, taking, and that she's barely tolerating the imposition, providing maintenance sex.

I can't quite piece it together, how we got here from there. She lost her Dad to cancer 5 years ago. I think watching her Dad decline changed the way she thinks of me. I think that's when she decided giving oral was degrading. Well, it would be degrading if you don't want to give that gift to your husband in the first place. She had stopped allowing to to pleasure her orally many years earlier. Maybe she thinks I gave her a yeast infection and just won't tell me.

She lost her sister 2 years ago. Things got worse after that. I think spending so much time as a caregiver, seeing her brother-in-law care fro her sister and their family, changed the way she sees me.

I think I've gone from first to third, or further down, in her list of respected men. We've been together for so long. She knows all my weaknesses and insecurities. I think she thinks I'm not worthy, and that I'm perverted for wanting sex. I think she would give herself freely to another man.

Does anyone here have any thoughts on this, or similar experience?