How do you know if a spell has failed? Is there a general timeframe? A rule of thumb?

How do you know when a spell has failed?

If some super hot lover isn’t waiting for me when I open my front door does that mean my love spell has failed?
What if it is a spell for money? If I don’t find a bag of gold on my way to the mailbox, has it failed.

From what I can tell, faith is about as important as intent.
When do you know that your spell has failed and you need to do it again.
Is there ever a time when you should assume the Universe/Creation does not want you to have something and you should stop asking for it?

I don’t want to “lust for results” but I also don’t want to be indifferent.
I am new to magick - I have no doubt that I am making mistakes. (although I only do the simplest magick, so I can’t be doing it too badly)
Divine Name/Candle/Psalm magick. I would guess is pretty hard to screw up, still, maybe my intent was off of something.