ἀδνός (adnos) is indeed Cretan Greek, but the strengthening prefix ἀρι (ari) is not (or at least not specifically so). It is mostly used in early Epic Greek and Greek lyric poetry: https://en.wiktionary.org/wiki/%E1%BC%80%CF%81%CE%B9-#Ancient_Greek (in English). [noted -ed]
In another version of her story, Theseus left her behind by mistake. When he returned for her, he found her missing, and presumed her dead, which deeply hurt him.