As written earlier, out of deep anger against his father (Lord Sun), Sani started doing penance. His objective was to become more powerful than Lord Sun.
During penance, one has to remain celibate and have to control his emotions and also to subject the body to extreme sufferings, like the sadhus or the rishis do. Lord Sani went through this process of penance for years and finally succeeded. While Lord Sun gave life to all beings, Lord Sani became the DEALER OF DEATH. He had the additional power of bestowing instant WEALTH & PROSPERITY and also THE POWER OF HEALING (by denying death). So, Lord Sani can be a foe (enemy) or a friend too if you know the "right button" to get connected, i.e. through mantras & tantras.
What happened then? Even after achieving his goal, he continued to be celibate and led a life of a hermit!
CHHAYA, his mother was alarmed and like any good mother forced Lord Sani to marry a girl of her choice believing the beauty of the bride would change her son's attitude. Unfortunately, no such thing happened, and Lord Sani continued with his daily meditation after going through the marriage rituals with extreme reluctance, only to please his mother. Probably he did not understand the responsibilities of marriage. As mentioned earlier, Sani matures only when he reaches 36 years of age. That is the reason when one has got his/her Saturn in his/her 7th House (the house of marriage), we astrologers, would suggest that late marriage would be a better idea, of course, subjected to other conditions too.
His wife tried her best to win him over, but Lord Sani did not even look at her. One day she had enough of it and CURSED Lord Sani by saying "Since you did not even bother to look at me, I curse you that whomsoever you look will perish"........takut!
That is why "SANI PAARVAI POLLAATHATHU"...like a movie title aaah!