てたまらない details
fun + unbearably X
tanoshi kutetamaranai
unbearably X; X so much I can't stand it — any strong sensation, physical or emotional
早く彼に会いたくてたまらない。
hayaku kare ni aitakute tamaranai.
I want to see him so badly I can't stand it. casual
昨日からずっと気になってたまらない。
kinou kara zutto ki ni natte tamaranai.
It's been bothering me endlessly since yesterday. neutral
- i-adjective stem
- na-adjective
- past
- polite
Examples
unbearably X; X so much I can't stand it — a sensation, physical or emotional, so intense it overwhelms the speaker
早く彼に会いたくてたまらない。
hayaku kare ni aitakute tamaranai.
I want to see him so badly I can't stand it. casual
昨日からずっと気になってたまらない。
kinou kara zutto ki ni natte tamaranai.
It's been bothering me endlessly since yesterday. neutral
一人で暮らすのは寂しくてたまらない。
hitori de kurasu no wa sabishikute tamaranai.
Living alone leaves me unbearably lonely. neutral
資料の誤りが多く、不安でたまりません。
shiryou no ayamari ga ooku, fuan de tamarimasen.
There are so many errors in the documents that I am unbearably uneasy. formal
Formation
自発の意味を持つ動詞のて形＋たまらない（気になって・思えて・泣けて）attaches to verb stem (special attachment){I-stem}くてたまらないattaches to i-adjective stem{NA-stem}でたまらないattaches to na-adjective
Related patterns
Similar
Both intensify a degree, but すぎる asserts the amount overshot what's proper (食べすぎる — a fault, too much), while てたまらない asserts the FEELING is unbearable regardless of whether the amount is a problem (嬉しくてたまらない is pure delight, not "too happy").
Near-synonyms, but てならない stays inside a narrow set of mental/emotional predicates (思われる, 心配, 寂しい) and reads written/reserved, while てたまらない takes any strong sensation — physical or emotional (痛い, 眠い, 嬉しい) — and is the everyday spoken default.