Simply put, the idiom is 'went to a lot of trouble' Not 'troubles' It's that simple.

I think you can't say 'troubles' because it is an uncountable noun. That's like the word 'bread'. We don't say 'breads' or 'a bread' in English, because it doesn't sound logical to us to count bread. Same thing with trouble.

Hi Victoria, In essence you can say trouble and troubles. Only thing is that 'troubles' implies that she went through different kinds of difficulties. This would beg to question: what kinds of trouble, can you name all of them. That is why the idiom is 'going to a lot of trouble', which means as much as: she made a real effort to help us. I hope this helps, Aleks

Whether or not you can say “troubles” depends on the meaning of “trouble”. Here "trouble" means “inconvenience/extra effort or work” and is uncountable (which means that it can’t be used in the plural). Other examples of “trouble” in this sense: “They didn't even take the trouble to call and let me know they'd be late.” “I decided that upgrading the software was more trouble than it's worth.” “Troubles” has a somewhat different meaning than “trouble” as mentioned above. It’s something more serious and unpleasant than “inconvenience/extra effort”. Examples of this meaning are: “She told me all her personal troubles.” “Your troubles are over now that he's out of your life.” “I have my own troubles to worry about.” “They've had some financial troubles since he lost his job.”

You can use troubles here but went through is the right expression. So the sentence would be :- Ruth was helpful, and went through a lot of ...............troubles.................. to make us comfortable.