"So I will trust someone until they give me reason not to but guardedly, and I would absolutely launch a search of their devices if I suspected they were cheating."
Me too. Being cheated on puts you (and your dependent children) in huge emotional, mental, and financial danger. How many threads have we read here where an apparently loving and doting H and father becomes a vicious POS to his stunned wife - and it turns out he's been fucking someone else. And some of those blokes also go on to dump their kids.
The spouse is also at risk of physical danger from STIs that could really affect not just her immediate health but also long term health.
Cheating is a very serious threat to the betrayed spouse, especially for women, because women still labour under a heavy burden of motherhood tax and tend to be not as well placed financially as men.
Let's be real: no one - NO ONE - is going to leave their marriage on the flimsy suspicion of their spouse cheating. There is just far too much at stake. That's why most betrayed spouses who suspect cheating spend inordinate amounts of time, energy, and mental health battling through the fog of the cheater's endless lies and then trickle truth trying to find out what's really going on/happened.
If I started seeing signs of The Script in my H, and it kept happening, I would 100% check his phone. Because if he is cheating, he's become my enemy, and I have to act to rescue myself and my children.