I was in the same boat. I was married for a long time to someone not adventurous in bed. Eventually we both amicably separated and I went on to one kink adventure after another. I got pegged by a domme not soon after and it was amazing. That orgasm was like no other. I started dating women more sexually compatible and it was all good from there. Don't get me wrong. Not advocating leaving. Just sharing my experience. There were other things that could have been better in the relationship. The grass isn't always greener on the other side. Anyway, watching a pegging video with a dildo in your ass and your imagination might be the next best thing.
The only woman I have been pegged by is my current wife, and it came about in a round about way. when we were together we started dabbling in anal play. nothing serious, just a finger or two, and small vibrators. then one night I asked her if I could truly have her ass. she was reluctant, because the only anal she had was with her ex husband, and he was entirely too rough and she hated it. I did ask a couple more times (just an occasional mention that I sure would like her “ sexy” ass. her stipulation was that if she gave up her ass, she got mine! So one night we’re going at it, and she acquiesced. lots of lube and prep And patience! of course, the initial “pop” hurt her a little bit, and I asked her if she wanted me to stop….”No, just don’t move”. can’t remember how long it was before she told me to keep going. OMG she really started getting into it, and had one huge orgasm. no additional stimulation, just me in her bum. the next morning I asked her about it, and she said surprisingly that she loved it! then she reminded me of her stipulation… I got hers so now she wanted her turn. Got online (dial up was a bitch), and did some research on pegging, and found a good quality strap on with the size that resembled my own. she figured if she could take my size, I should have to take it also. a big grin and her eyes lit up when she opened the package a couple days later. we had a romantic weekend planned in a nice hotel suite locally…. just to get away from family and friends. I took a quick shower, was sitting on the bed, and got the shock of my life when she walked out of the bathroom, wearing nothing but the strap on and carrying a tube of KY.HOLY SH*T. I didn’t even know she had brought them with her. needless to say that was a great night…. started doggy, then missionary, and the finale me pressed against the shower wall with her behind me. WHAT A NIGHT! things progressed from there, and we would have scheduled “A” nights a couple times a month. schedule because we could do our personal prep, and knowing that day was coming soon, had us both wound up! One thing some folks don’t mention, is the role reversal that pegging involves. Normally, we were very give-and-take during normal sex…. however you want to define that…. but when she was the receiver during an anal, she became quite submissive. when it was time for pegging, she became quite dominant! I loved it, seeing this somewhat dormant side of her. Sadly, now that our age menopause has taken its toll, so no sex at all with her. the only bum fun I have is solo. Still have that strap on dildo, and I bought a similar sized suction cup version. As @wayneG99 mentioned, if you’re not getting it from your partner, put on a pegging video and have some solo fun.