After a lot of research, talking with others, and some experience, I sort of realized that sometimes they just have to get frustrated, have tantrums, etc. ... My understanding from UP is that we don't have to eliminate all struggles but honor their feelings about them.
I come from a family of "fixers", people who hate to see other folks upset, and who do everything they can to "fix" it. What that really means is that as a child I was immediately distracted from anything that upset or frustrated me, and so I unfortunately earned that it's not okay to struggle with something difficult, nor is it okay to show your true emotions. I was told, "It's okay" when it wasn't, and "You're all right" when I wasn't. To this day, I cannot turn to my own mother when I have a problem I need to vent about. She wants to "fix" it rather than listen to what I'm really saying, and it's incredibly frustrating.
I have had to really work on myself in the last year to avoid doing that to my son, but the results have been good. He is able to work through his own frustrations in ways that I would not have thought possible, all because I sit back and let him. I stay close and tell him I will help him if he asks me to, and sometimes he will look up at me and say, "Mommy help?", but most of the time he will ignore me and plow on through until he makes it work on his own. What a great skill he is learning for life!
I think that is something UP has taught me, and it's made me a better parent, friend, and partner. :-)