Talking specifically about your 5th point, I can relate. The 2009 NFC Championship game was the final straw in my HARDCORE fandom for a team. Embarrassing story.... Myself and college roommates at the time were throwing beer cans, water bottles, anything of note in anger because of what we were seeing on the field. After the loss, we were all so devastated that we cancelled plans for the rest of the night. Woke up the next day still livid about the result... After that, a moment of clarity hit that it was just entertainment, and I've never let a result of a game affect me that way ever again.
Same here, the Saints Championship game was a turning point for me as well. After that post-game depression, I came to the realization that the Vikings will never win a Super Bowl in my lifetime and I am OK with that. Having lived through 4 Super Bowl losses, the 1998 Championship game etc..that was enough. When Blair Walsh shanked the FG against Seattle in the playoffs - I was like yep that is what we expect. Getting back to the OP - I do find myself less interested in watching football lately. Hard to put a reason for it but some combination that I have hit 50 years old, the games/teams start looking the same to me (maybe related to getting older or it seems like everyone runs a similar passing-based offense), I don't have the DirecTV package so you get stuck watching the same teams on Sunday afternoons, I live in Dallas/Ft Worth so I get the Cowboys shoved down my throat. I have actually enjoyed College football more lately. I stopped playing FF a couple of years ago after playing for 20 years and I do not miss it one bit.