Eclipse:
Why, those are easy ones even I could attempt.
1) Let’s assume it’s an older girl. She sops her pillow every night, every other girl’s simcha is another stab to her delicate heart. So one night she bravely paints over a smile, a new look, a bright gaily attitude and ventures out to a friend’s chasuna. She wants her personal misery now definitely forgotten, put aside. She put much effort into this venture, she may not want to be (again) reminded of her sorry state. Of course there’s a way to tell her, AND I’M SURE YOU KNOW BEST, but that’s the answer – why sometimes one will be angry.
2)That may be because this is an olam hasheker so falsehood roams freely. Sometimes falsehood can be made so polished, so convincing that it’s more readily believed than emes. But don’t worry, as the Gemarah says, Sheker ayin lo raglaim, it has no feet (as all letters shin kuf and reish have only one leg, as opposed to emes alef meme suf which have two), will not stand long, will eventually dissipate. The Emes will eventually shine forth.
3)Tehillim may be said on Shabbos, as you noted, it’s the most relaxed time. It’s the opportune time to connect with Hashem, especially through those words. It’s just that one musn’t say bakashos on Shabbos the way one does in the weekdays, that’s lessening the tranquility of the day.