Is reading Surat Ya-Sin, performing Salatul Hajah and Istikhara, and then feeling at ease, considered proof that the relationship between a young man and his maternal aunt's daughter is permissible and blessed?

Istikhara (seeking guidance from Allah) is legislated, and among its effects is the expansion of the chest (feeling at ease). Supplicating for marriage to a specific woman is permissible, and there is hope that the supplication will be answered, especially during the last third of the night. After consultation and Istikhara, propose to the girl from her guardian. As for the saying, "Yasin is for what it is recited for," it is not a hadith. It must be noted that the girl remains a stranger (non-mahram) until the marriage contract is concluded, so seclusion with her or looking at her (with lust) is not permissible.