This has been my experience as well. Much of that was not coming from my husband, but from internalized expectations, which I am now free to disregard, with the full approval of my partner. I get that non-monogamy isn't for everyone, but I also think that a lot of people don't realize how well it might work for them because they've been so indoctrinated into monogamy being the only possible, ethical, honorable thing to do. Your story really is a prime example of how a somewhat stagnant relationship got totally revitalized just by changing up some of the "rules."