To Suffer
To Struggle
intransitive verb, godan verb
You've already been introduced to the word 苦しい. That word means painful, or agonizing. So, if you turn that into a verb, you have to suffer or to struggle.
くるしむ
The reading comes from 苦しい, so as long as you're on top of that word, this word should be readable for you as well.
トーフグの考え方は、理かいに苦しみます。
I struggle to understand Tofugu's way of thinking.
はんざいに手をそめるようそそのかしてくるコウイチからの強れつなプレッシャーに苦しんでいます。
I'm struggling under intense pressure from Koichi, who aided and abetted me in a crime.
なぜ罪のない人が苦しんでいるのか。
Why do innocent people suffer?