I'm upset that someone won't spend meaningful time with me even though they are really busy.
Why wouldn't they spend meaningful time with you?
They find it more meaningful to spend the time by themself than hanging out with me.
You shouldn't expect someone to always have time for you. They may be very busy and not have a lot of time for anyone. Just wait a bit until their life frees up a bit.
That's too long a wait. I'll find a new friend.
Well you could get more friends, that's fine. But sometimes people are busy.