Between this and his knowledge of all the terrible disasters that have fallen the MCU, this is a man for whom time travel is both a gift and a curse. It's swell that he gets to live a life with his one true love, but he has to spend that time closed off from current affairs, lest he let something slip and irrevocably screw up the timeline.
And let's face it, Cap is a great guy. Those years spent nervously sweating whenever someone offhandedly mentioned Dealey Plaza or the Twin Towers would've killed him. He would've had to relive everything again, a life stuck between the rock of saying something and breaking time and the hard place of not saying anything and getting his happy ending.