How to choose between ずにはいられない・てならない・ざるを得ない・てたまらない when saying "Can't help but..."

Question

Can someone highlight the similarities and differences between all terms that have a meaning of "can't help but …" ?

Examples:

詐欺{さぎ}にあった気{き}がしてならない。
I can't help but feel it was a scam.

彼{かれ}の生{お}い立{た}ちを聞{き}いたら、同情{どうじょう}せずにはいられない。
Hearing his story, I can't help but feel sympathy for him.

自分{じぶん}の子供{こども}のことを心配{しんぱい}でたまらない。
I can't help but worry about my own kids.

彼{かれ}の辛{つら}い状況{じょうきょう}を見{み}て助{たす}けないではいられない。
Seeing his suffering, I can't help but feel like helping.

Answer 1

• ～てならない: This is usually used with 気がして, 思われて, 考えられて, or sometimes negative feelings such as 腹が立って, 恐ろしくて, かわいそうで. It means "cannot help feeling ～" or "some emotion/feeling spontaneously occurs to me".
• ～てたまらない: たまらない on its own means "unbearable", so this explicitly describes how the said feeling is troubling you. 恐ろしくてならない and 恐ろしくてたまらない are interchangeable, but the latter sounds you are very afraid.
• ～ないではいられない, ～ずにはいられない: These tend to sound more proactive and emphatic. 助けないではいられない usually means you do want to help someone, not reluctantly nor passively. As compared to passive ～と思われてならない, ～と思わないではいられない is usually a way to emphasize your way of thinking is correct. In other words, 思われてならない is closer to "I kind of feel ～", whereas 思わないではいられない is closer to "I must say ～". The difference between ない and ず is very small in this case.