It can't have been easy for her, ever. Consider this.
Her husband was cursed by his mother and blessed by his protector. Lleu's mother had said that he would have no name but for the one she gave him, would carry no armor but for the arms she gave him, and would have no wife that was born of woman and man. And, so she decided, she would do or provide him neither of these things.
Effectively, she told him he would have no identity of his own. Not having a name makes him a "non-person" in mythological terms, without arms he has no option to "make a name for himself" as almost all quests of that kind would involve prodigious fighting, and without a woman by his side to bear him children, what good would his life be, from a mythological perspective?
Luckily, or unluckily, he was also blessed with near-immortality. He could not be killed inside or outside, not on a horse or on the ground, not in water or on dry land. There are ways around this, and such is the crux of his tale. Blodeuedd, however, had her hands full with herself.
His protector, Gwyddion tricked Mama Lleu into giving Lleu name and armor, and created for Lleu a woman made from flowers and plants. She was beautiful of form and her face was like a flower, and so she was named Blodeuedd, which meant Flower Face, and all was good.
But Blodeuedd, not being human, could not feel as humans do, and the seasons and the changing of the world affected her greatly. Like a plant, she had no concept of human warmth and love, and like a flower her appearance served but one purpose. She was unfaithful almost from the very start, but Gwyddions magic ensured that she could have children only by Lleu.
Never having been born, she was unable to grasp the concept of death, and her natural curiosity and naivety were used by her lover to betray her husband. Besottedly in love and trusting with it, Lleu explained to her that he could be killed, provoding he was with one foot in a bath of water, and the other on a goat, and half underneath an overhanging roof, and that the blow that struck him killed him immediately. Blodeuedd quickly told her lover, who just as quickly disposed of the troublesome Lleu.
Gwyddion, never a man to quickly relinquish a project, decided to pay Blodeuedd for her (unavoidable, instinctive, predictable) betrayal by chasing her up a mountain and in front of her eyes throwing every single handmaiden or chambermaid in her service down the jagged rocks. Blodeuedd, by now thoroughly inundated with the concept of death, and therefore fear, was cowering at the mountain's top while Gwyddion enjoyed himself killing the last of her friends.
At the mountaintop Gwyddion cursed the lovely woman he created, and turned her into a snowy screech-owl, hiding her from the light of the sun. She was forced to hunt the nights, forever. Her face is still like a flower, but the colors turned to deathly pale, and where she was admired by all for her beauty, now other birds resented her, and attacked whenever she came near.
The accepted moral of the story is "Never trust a pretty face" but I would much prefer this to be a teaching along the lines of "If a beardy old man makes you a woman out of flowers, ask him if he's given full thought on possible outcomes of his choice of recipe"