Everyone intended to ignore first serious relationship (8)

I believe the answer is:

alliance

I'm a little stuck... Click here to teach me more about this clue!

'serious relationship' is the definition.
'alliance' can be an answer for 'relationship' (thesaurus). I am unsure of the 'serious' bit.

'everyone intended to ignore first' is the wordplay.
'everyone' becomes 'all' (all people).
'intended' becomes 'fiance' (who someone intends to marry).
'to ignore first' means to remove the first letter (I've seen 'ignoring first' mean this).
'fiance' with its initial letter taken off is 'iance'.
'all'+'iance'='ALLIANCE'

Can you help me to learn more?

(Other definitions for alliance that I've seen before include "Union for mutual benefit" , "Wanting marriage" , "Formal agreement" , "Combination by treaty" , "Marriage - union" .)

I've seen this clue in The Independent.

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