Shit I don't know what suha been thinking it's just he already know that red haired guy will not gonna follow the deal or whatever stuff they talking about.
Gosh suha he can do better than that...
SPOILERS.....
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I think because red haired dude drugged Jiwon (did I spell that right?). And it seemed like he was gonna call someone, threatening Suha. So most likely Suha had no choice and to protect Jiwon. And from the looks of it, after the kiss Suha started crying.
But you can't be sure if the red haired will keep his word.
Bruh I read the raws and are we really DOING THIS SUHA???? ARE WE FR?? I THOUGHT YOU KNEW BETTER