I'm upset that my husband did not celebrate my birthday
What was it that hurt you the most about your husband missing your birthday?
It means that he doesn't care about me anymore. He told me he was going to get me something on that day but he didn't.
To some people, a birthday is just another day. You should not get too upset if they do not get as hyped up for your birthday as you do.
I feel like he doesn't care about me and our relationship.
Maybe he doesn't realize how important your birthday is to you. He might not feel they have any special meaning, but that doesn't mean that he doesn't care about you. Tell him how you feel and maybe put your birthday into a proper perspective in terms of importance.