I know many identical stories. Unfortunately, many people are too dependent on the opinions of others. And not everyone is able to withstand this pressure. After all, Elizabeth and Philip were clearly not the only ones who considered Camila an unsuitable bride at that time. Were they ready to overcome it then? I think no. After all, Kate wasn't the most suitable bride either, and they weren't always together either.
In any case, I think the Charles and Diana case taught the royal family a lot.
		
		
	 
I don’t think Kate was ever seen as unsuitable. Maybe some really posh people didn’t like her roots but a lot of the aristocratic girls my understanding is didn’t want to Date William and be Queen.
I think the palace did learn from what happened with Charles, Andrew, and Anne’s marriages.
Edward’s marriage worked well and he married a mature woman with a career who he dated for years.  My understanding Edward was very clear he was going to make sure any woman he married had a really good idea of what she was getting into. 
And William clearly was doing the same with Kate.
 (A part of me thinks some of their break ups were circumstances and also I suspect William deep down wanted to see what Kate would do if they broke up )
I don’t think the problem was so much that Charles couldn’t Mary Camilla. My understanding is she did love her first husband. 
But that he couldn’t marry someone like Camilla.  
I think it’s very likely he did try to make the marriage work.  
But the two of them barely knew each other and had a huge age and temperament difference. Camilla may have nothing to do with why it didn’t work,
I am a firm believer that there isn’t one person there can be many one can make a relationship.  
It’s very possible if Charles had been given more lead way without the stupid virgin bride stuff ( and I say this as a religious person) that he would have married a woman  closer to his age with some life experience that he knew well like his brother