Story of Shani Dev cursed by his Wife
As per an ancient story, since his childhood Lord Shani was a keen devotee of Lord Krishna. When his father Lord Sun married him to Sangya a skillful daughter of Chitrrath, He (Lord Shani) used to remain absorbed in the deep thoughts of Lord Krishna. One day, his wife came to him, after having taken a bath after her mensuration period, At that time Lord Shani was deeply absorbed in the deep thoughts of his deity (Lord Krishna).
He didn’t even care to glance at his wife. His wife got much depressed and cursed him, “You may not be able to look at some one in future, and your sight would remain ever downward. Whomsoever you look at, he would be ruined away." When she overcame of her rage, she repented a lot, but the curse could not be get undone, so the sight of Lord Shani remains downward forever.