I think that's more of an age thing. Im nearly 40 and in a damn near perfect marriage for 15 years now.
We have friends that we absolutely find attractive. Frankly speaking, we all take care of ourselves and it shows.
Im not looking to bang any of them, and my wife isnt either (granted, as she says, but we have a very strong relationship). We're happy being friends, being comfortable going to the beach, hitting the gym together, etc. We're all very happy in our monogamous relationships (minus one couple, because he fucked around and is now in the 'finding out' stage). Life isnt porn?
It sounds like you're more grappling with maturity, and maybe a bit of heartbreak.
Hey, this explains my daughter's birth, 13 years after the fact!