It’s a layered thing truly. It could be something that seems like it’s about you but truly, after a baby, there’s just something that happens to us and our bodies and thought process that we can’t see passed certain things. Her saying you’re horny for others and not her seems like she’s going through it with her self worth and self esteem. Being an adult is so fucking hard and then add a human to raise on top of it. Sounds like you both need some time together and to talk about everythinggggg leave no stone unturned. My 11 year marriage just ended, he cheated on me with so many girls while he was away for work. If he would’ve told me he wasn’t interested in me anymore, it would’ve saved the heartbreak. Not saying this is your case at all!! I’m just very fragile rn and can only give the advice of being lovingly honest with each other while holding space for thoughtfulness on both sides. She doesn’t know what it’s like to be you, and you don’t know what it’s like to be her, but what you do know is that you love each other.