I think also that is another reason Bella always believes Edward, because even if he is lying, Bella knows deep down inside that he wouldn't without a good reason.

Edward is sincere and that counts for a lot!!!

Not to lessen the impact of your story but I find that most kids are literal. They remember almost anything you say and will repeat it to you verbatim. It's very hard to come up with acceptable excuses for kids when they remember that you promised them something. You teach kids to keep their word, to not lie and yet you (whomever) isn't keeping up their end of the bargain and it makes learning/understanding confusing. I found this out the hard way with my cousin and then later with my Little Sister. I learned not to make a promise or say that I was going to do something when I knew there was the slightest of possibilities that I might have to back out.