I see so often on MN where the OP has a genuine dilemma over attending an event or meeting an obligation or having visitors or some such, loads of advice to 'just say... [insert random lie here]' when actually the truth is perfectly fine.
It's happened to me this weekend, a friend cancelling dinner on Friday with an excuse that (without going into detail) I know isn't true.
It's obvious that she just couldn't be bothered to go out at the end of the week, and if she'd have said that then I'd have been fine, I was fine with her cancelling anyway, I expected it (she's got form for being flakey) just a bit
that she's felt the need to make up some dumb excuse.
So, AIBU to wonder why people feel the need to lie or encourage others to lie, especially in circumstances where the truth wouldn't hurt any feelings or make any difference to anyone, and in fact sometimes might be beneficial for the person being lied to to know!