Welcome to MarriageBuilders (MB), Brad...
You've been led to a great place to save your marriage. And I believe a wonderful choice you made in posting.
Have you been reading all the articles on the website? There are links to the right of your screen...Basic Concepts, Rules of Marriage...the Love Bank.
You're on the resolving conflict forum...and I infer from your post that the conflict you see is your wife believing one thing, and you desiring her to believe something else?
What she said about not loving you...is a red flag for infidelity. Doesn't mean, necessarily, she's sleeping with someone else...or that there is an actual someone else...humans can believe in "someone else" that force of "the one" and betray their marriages within their minds, choice of beliefs...rewrite their marital history and not understanding they are blocking the love they are feeling with resentment, entitlement and a lack of respect.
I suggest posting in Infidelity General Questions II forum, or Emotional Needs forum...GQII has the most traffic, and EN has more than RS (resolving conflict).
Often, a new job is a tiny red flag because of being exposed to new people and ideas...and presenting the idea of who you are to others...like a clean slate...is another element necessary in adultery.
This may not be true in your marriage...depression, patterns of withdrawal/pursuit, lots of other dynamics might explain her current belief...I'm with you--she didn't have this belief when she married you...baby or not...if she was firmly committed to doing what is best for her daughter (being married to her father), then her belief would be making your marriage the best it can be...not looking on it like a debt, an error...
I share this with you because I experienced it myself...after 14 years of marriage, I rewrote my history, called my love a debt, fully paid, and went wayward...I'm not talking about what I didn't live...and it took a lot of me creating and holding onto resentment, building it into entitlement, and living a life lacking respect, for others and for myself.
Whether she is in a wayward state of mind, or not, learning that love is a choice, which generates a feeling, and that acting on our belief of love, results in loving acts...is a better way to love than believing the amount of love you feel at any given time, determines whether you love or not.
LA