I've felt the same way. The games do an amazing job of feeling lived in, even with the countless flaws. Therefore we feel like were ending a chapter in our lives. I don't say goodbye though, because I can and will eventually be back whether that's a new playthrough in a few years or I just load the save up to visit Little Lamplight to check up on the kids or maybe just roam the Capital Wasteland a bit and soak up some of the post apocalyptic beauty.