You answered your own question.
If he’s warm and caring all other times, it must be that he doesn’t know what to say. A lot of guys turn into deer in headlights when a woman is upset. They don’t know what to say and they don’t have confidence in their own ability to comfort you, so they just detach.
Knowing how to encourage someone who’s down is a skill that takes practice, and a lot of guys get no practice until they are in a relationship. You become their learning curve, and a big part of any learning curve is failure.
Obviously, you need to tell him how you feel: isolated, neglected, like you’re his mother. Remind him that you need to be comforted just as much as he does when things go wrong. But more importantly–this is key–tell him that he doesn’t have to be Dr. Phil to help you. Guys tend to lack confidence because they don’t have some groundbreaking insight into your dilemma, but all you really need is someone to listen and say, “You’re right” and “I’m sorry” and “How can I help?”
It took me a while to learn this as a husband. I’m a problem-solver by nature, so when my wife would come to me with a problem, I would start telling her what she needed to do to fix it instead of just shutting the hell up and listening. You don’t need solutions at that moment; you need love and support and a shoulder to cry on. You need an advocate and a friend, not a dad or a brilliant therapist.
Tell your guy this. All he needs to do is commiserate and listen. It’s not hard; anyone can do it. Even him.
Thanks for the question.