Diplomatic recognition is the biggest thing that is preventing full Taiwan Independence. If Taiwan can simply claim that they are a country and a lot of countries in the world recognize it then its over for China. They will not be able to get Taiwan back. One China policy is the only thing preventing Taiwan Independence.
China must pay a big price to defend One China Policy. They must either break relations with any country that develops relations with Taiwan, including US and Europe, which will lead to complete decoupling between China and US, and massive losses economically. Or they start the takeover of Taiwan through fighting, which has its massive challenges.
No matter how you look at it. This is a big problem for China with no way out. They either give up on Taiwan or start a new cold war and potentially hot war with the west to defend One China policy. The west wants to start a cold and hot war with China. So, they don't care about rising tensions. They welcome it. Taiwan's DPP also welcomes it cause they think it will boost their support.
The only way out for China is pressure Taiwan massively and put the fear of death and destruction on them to back down from this. It must be Taiwan that must stop contacts with the west cause the west will not stop it. They will increase it. So, China must do something to threaten Taiwan now. Its either taking an island or flying directly within Taiwan. If Taiwan stops contact with the west to reduce escalation and shows some pro-China behavior, then things could be good for China. Otherwize, China is in big dilemma of either fighting a war or losing Taiwan for good.
Highly superficial view.
China is not in any dilemma. China identify herself as the only big power that has yet to complete her sovereign unity:国家的领土主权统一. And thus reunification has been the main theme/cause for their rise all these decades. On that idea, proceed instead to ask the US and allies how much lives and economic cost are they willing to throw away merely for a CAUSE(preventing reunification of china) which otherwise is not even remotely beneficial to them other than to offer a leg up at preserving their fake front of promoting democracy and human rights.(Do US and allies actually really cares about those values? Their actions around the world indicate no).