The most common and most likely answer to this crossword clue is the 10 letter word DALLIANCES
I've seen this crossword clue in The Guardian
D
A
L
L
I
A
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More clues leading to the result DALLIANCES
Buddy explains!
The straight part
We know that "Ultimately short-lived relationships?/Ultimately short-lived relationships?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ultimately short-lived relationships?/ultimately short-lived relationships? = dalliances.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does DALLIANCES mean?
DALLIANCES noun- Playful flirtation; amorous play.
- A wasting of time in idleness or trifles.
- A sexual relationship, not serious but often illicit.