Where does “愛して” come from?

愛して (Japanese) comes from Japanese て, from Japanese つ, from Old Japanese つ.

Ancestry of “愛して”, step by step

愛して traces back through two separate lines of ancestry.

via Japanese て

StepLanguageWordMeaning
1JapaneseてA conjunctive particle, attaching to the...
2Japaneseつindicates the completion of an action; indicates...
3Old Japaneseつ—

via Japanese 愛し

StepLanguageWordMeaning
1Japanese愛しdear, loving; loving
2Japanese憂し—
Every word from Old Japanese つ →Every word from Japanese つ →Every word from Japanese て →