切ない vs. 苦しい：Do You Know Which Should We Use?
When looking up both “切ない” and “苦しい” in your dictionary, they would be “Painful”, so you might’ve got confused about them. Let me introduce how you correctly figure them out today!
Painful / Feel So Sad / Miss
“切ない” means “Painful, Feel so sad and Miss” which has been often used after breaking up with your partner and when your friends left your home, unlike “苦しい”. Everyone could use “切ない” as casual, polite and formal such “切ないよ。(I feel so sad.)” as casual and “切ないです。(I feel so sad.)” as polite and formal.
Painful / Hard etc…
“苦しい” means “Painful, Hard, etc” and which has a lot of meaning such as after breaking up with your partner, “胸が苦しい。(It’s breaking my heart.)” has been used and after eating a lot, “お腹が苦しい。(I’m so bloated.)” and “鼻が詰まってて苦しい。(I can’t breathe.)”, etc. Everyone could use “苦しい” as casual, polite and formal such as “お腹が苦しいよ。(I’m so bloated.)” as casual and “お腹が苦しいです。(I’m so bloated.)” as polite and formal.