Comes from だ + とて. Very often with なん in front, becoming なんだって. It generally exclaims that something was the premise for something else.
Even (...)
is a conjunction that means 'even (...)', or '(...) too';
It's an #casual version of でも
it puts emphasis on that, contrary to expectation, it also holds for someone/something else.
私だってあなたに会いたい。 I too, miss you
誰だってそんなことは知っているさ。 Literally everyone knows that (you're not special)
彼だって落ち込むこともあるよ。 There are times when even he feels down. (informal)
Because...
almost always has a negative connotation.
え〜行きたくないよ。だって、俺の元カノも誘ったんでしょう？ I really don't wanna go. (the premise for that being that) my ex-girlfriend is also coming
だって、サメとか怖いもん。 it is because I am scared of sharks.
Hearsay
describes Hearsay It's just the explanatory の・んだ with だって
お母さんの実家は 農家なんだって。 (apparently) mother's parental home was a farmhouse.
for verbs, goes with the i-stem
明日から一週間休みなんだって apparently, there will be a free week starting tomorrow.
サクラちゃん来年結婚するんだって。 apparently, Sakura-chan is going to get married next year.
そうだ vs らしい vs みたい vs ようだ vs なんだって
https://bunpro.jp/grammar_points/だって https://bunpro.jp/grammar_points/んだって