there are some things that I choose not to be skeptical about: my wife and everything about her, such as the her not cheating on me, her not being a crack addict, her not beating the children, her not racking up 1000's on the credit card, her honesty about her life before we met, that she's not stealing money from my friends, etc. I don’t have to be skeptical about those things because I have solid evidence that they are false, because I love her and she loves me, I can feel it.
In general, this is how most of us think. We feel love towards a spouse and we observe generally good behavior from them. Therefore we tend to think that there is not any bad behavior hidden from us.
So what happens if your friend confesses that he has been having sex with your wife? Or you find drugs in her purse? Or the kids confess that they are really afraid of your wife because she beats them while you are at work? Are you still going to "choose not to be skeptical about her?" After all you still love her, and she loves you, and you can feel it. Why choose to be skeptical at this point?
Of course any of those revelations would radically alter your relationship with your wife, no matter how good you felt up until that point in time. But to a priori refuse to not be skeptical is to is to essentially admit that you don't mind being lied to, as long as you feel good about the situation. And that, in essence, is the problem with Mormon epistemology.
My main point is that for the most part, we do operate on auto pilot throughout life. Generally good behavior from a spouse, associated with good loving vibes, is pretty good evidence that the marriage is fine. But what do you do with really big disconfirming evidence? As a Mormon, you are taught to ignore it.
For me, the "witness from God" (a.k.a., good vibes/feelings) is a legitimate form of evidence. But, it's only one piece of evidence. If there is other contrary evidence, you have to re-evaluate or re-interpret the good vibes/feelings. In some cases the evidence will kill the good vibes/feelings. For example, finding out that a spouse has been cheating on you will turn warm loving feelings cold very quick. In my case, one of the reasons I hung onto the LDS church for so long was because of a general respect I had for Joseph Smith. Learning about Helen Mar Kimball finally killed that for me. Facts influence feelings and vice-versa. Mormon epistemology likes to pretend that feelings are totally separate from facts, and works very hard to convince people that they are separate.