You've made some excellent points.
For me, the transition from being a sex maniac - jumping from bed-to-bed - to settling down in a monogamous relationship was done quite intentionally. My life prior to retirement was divided in two parts: Work and Play. With 6 months of non-stop work in the U.S. which involved constant travel - to 6 months in Thailand which involved constant sex. For me, this was the perfect balance.
The lifestyle I wanted for myself after retirement involved "Balance"...which was missing from the lifestyle I just described above. The things I felt that needed to be balanced were; Health, Social Interactions, Finance, Hobbies/Me Time, and, last but not least, Romance, Intimacy, and Sexual Fulfillment. It's not that I felt myself being more introspective about sex, or for that fact, more inclined to be in love with someone either, rather a desire to have a more balanced and healthy lifestyle when work was no longer a necessity.
When I returned from my morning stroll along the shoreline today he was standing on the balcony wearing only his boxer shorts which had slid well below his slim waistline. He turned around to face me and asked if I had any luck finding clams. I said yes, and showed him my bucket which was half-filled. Then he gave me one of THOSE smiles and asked me if I was hungry. My clam bucket sat unattended in the kitchen sink for the next hour...and the day has only begun.