乍见之欢处久不厌
[zhà jiàn zhī huān chŭ jiŭ bù yàn]
'Joyful at First Sight Yet Not Annoyed After Long Time Stay' talks about both first impression attraction AND long-term relationship compatibility - meaning people feel happy when they meet each other for the first time but also find each other comfortable and pleasant over time rather than getting bored quickly.