My cousin just keeps on planning that we will go here, do this, do that..... but it never happens. And in the next meet also the same cycle repeats. So I was just wondering what is the appropriate word for the things that are planned but never happen?
a wish or inclination not strong enough to lead to action.
- ‘the notion intrigued me, but remained a velleity’
Definition supplied by Lexico
Hypothetical plan? :P No, I'm kidding. I would say the word would describe your cousin rather than the plans he keeps repeating.
The first word that comes to mind is "flakey" which is slang - the non-slang terminology for it is undependable, basically. Another way to describe him (meaning the same thing, just a different word) would be to call him unreliable or fickle.
If you didn't want to be overly harsh or rude, you could say he's uncertain, indecisive, unpredictable, or inconsistent.
You could use warhorse.
3: [often premodified by 'old'] something ([perhaps] a work of art or musical composition) that has become overly familiar or hackneyed due to much repetition in the standard repertoire [/course of events]
Usually used in the arts, but readily transferrable:
Is the Atlantic City boardwalk and beach safe at night?
Oh, my goodness, not this old warhorse again. It's been debunked on this forum many times. Hint: crime figures are compared to the city's population, but don't take into account the number of visitors to the city.
[ShiannM; Trip Advisor ... Forum] (punctuation corrected)
I think the word materialize is more apt in this context. It means:
to begin to happen or exist : to occur or become real — usually used in negative statements
For example, She was promised a promotion but it never materialized. Source: https://www.britannica.com/dictionary/materialize
So, maybe you mean: We had planned a vacation together, but the plan did not materialize.