He wanted to leave _ he stayed until the end.
- But
- So
- And
- Because
Explanation
"But" is used to contrast two ideas.
The first clause shows intent to leave, and the second shows he didn't, so contrast fits best.
He wanted to leave but he stayed until the end.
(وہ جانا چاہتا تھا لیکن وہ آخر تک رُکا رہا۔)