Success or failure of married life’s are based on kundli Milan or ashtakoot milaan. If best gun of couples meet then their married life turns successful & lasts longer.
There are mentions of eclipse causing "demons" in the Atharvaveda and Chāndogya Upaniṣad, the Chāndogya mentioning Rāhu 382 In fact the term graha, which is now taken to mean planet, originally meant demon. 381
YAGYA means sacrifice, prayer, worship & total surrender to God for the achievement of desired results. This desired result may be good education, financial gain, development of business, good health, freedom from bondage etc.