Ultimately sad break in relations leads to indecisive state (5)
I believe the answer is:
drift
'indecisive state' is the definition.
'drift' can be an answer for 'state' (I have seen 'state of indecision' mean 'drift' so perhaps 'state' could also mean 'drift'). I'm not certain of the 'indecisive' bit.
'ultimately sad break in relations' is the wordplay.
'ultimately' indicates one should take the final letters.
'break in relations' becomes 'rift' (I've seen this before).
The last letter of 'sad' is 'd'.
'd'+'rift'='DRIFT'
'leads to' acts as a link.
Can you help me to learn more?
(Other definitions for drift that I've seen before include "Movement off course or in general" , "Move with wind and tide" , "Move casually or aimlessly" , "go with the tide" , "Float with current" .)