As a married man it's normal to feel that way from time to time. We just had our 3 year anniversary and there have been times that I've wondered what it would be like with another woman and she said she's wondered the same thing. The difference is, that you have to be willing to communicate or you're doomed. I'm not saying that sex is the most important thing in a relationship, because it's not, but trust me when I say this; when things are going shitty financially or w/e, is there isn't much in the bedroom, then it makes things ALOT worse. It's just another bullet in the gun. One thing that I've always been thankful for is me and my wife's communication. She's always open to trying new things or taking suggestions as to what I like. Believe it or not, not everyone LOVES sucking cock or eating pussy, they do it to please their partner. If you're doing a shitty job of it, then it's just a wasted effort. So talk to her, ask her what she likes. For example, sometimes I'll switch it up when eating her out, whether it be flicking my tongue in another direction, using just the tip, or more wide spread, or faster, slower, harder, softer, and she usually lets me know if she likes it best like that. Just a few suggestions for ya bro. I wish you the best man, gl!
P.S. Finished reading your last response lol, on another note, (this may not work for everyone as all people are obviously different but) what I do sometimes when she's not in the mood is I just mess around with her until she IS in the mood. Whether it be a massage, rubbing her back, a titty grab or lightly stroking her labia. Sometimes that does the trick. Don't always expect the horny mood to just be there, be creative and make it happen.