Enthusiasm Is Not Transferable
A lot of the time, you feel that your excitement about a particular topic or piece of conversation isn't being reciprocated in kind. You realise the other person isn't as interested as you thought they'd be. They're listening to what you're saying out of courtesy, not attention. They won't remember most of the conversation by the time you circle back to it.
This feeling deflates us, because we assume the other person isn't interested in us. We forget that most of the information we share is out of context, and frankly, absurd to the listener. Your excitement is born out of many factors, not a single simple act. Say you're getting promoted and you tell your friends about it. They'll be happy that you got promoted, but they won't share the same enthusiasm you're feeling.
Your enthusiasm is a byproduct of many things: the effort you put in, the politics you survived, the challenges you overcame, the sheer desperation you endured in the hope of that promotion. All of this comes together to form the enthusiasm you share with others, expecting them to hang on every cheerful detail.
We need to give people the space they deserve. They'll be happy for you, especially if they're family, but you cannot expect them to be as upbeat about it as you are. And if they aren't, that's not on them. You shouldn't blame them for not grasping the context. There are times they watch you work hard on a project and wish you the best. When you eventually succeed at whatever you set out to do, they're happy, because they wanted your hard work to be rewarded. But even then, they cannot feel the same relief you feel in that moment.
Enthusiasm is personal, and someone devoid of your entire context might not be able to share it with you. Understand that if they're trying to participate in your joy, it means they love you. They simply lack enough context to be as jubilant as you are.