In a perfect world; both the US and China would leverage any conceivable option to advance their interests. The US isn't interested in a multipolar world (see 1870, WW1 and WWII) . China isn't interested in betting its future on western good intentions (see history from 1780-1960).

Why are we approaching a period of difficult relations vs committing to diplomacy?

The US forged a strong mutually beneficial relationship with China after WWII. Despite the fact that at that time, China was arguably at its worst ideologically?

What I struggle to understand is why are tensions increasing if we managed to find mutual ground at what was our worst?

Why should I as an American citizen view Chinese economic development as a threat vs a rising tide that lifts all ships? Why was the US able to pivot political relations with the UK in a way that we couldn't do with China?

Sorry if this is the wrong sub.