Arthur Clennam's age inappropriate love interests

I am half way through the book. I almost regret watching the BBC series from a few years back, good as it was, because I know what happens.

I am not a feminist, but I wondered what feminists would make of Mr Clennam's relationship with the eponymous Miss Dorritt. Mr Clennam was in his early to mid 40s, I think. Amy Dorrit was 23. When Clennam first came back to England from China, he looked up his own girlfriend, Flora, who was by then widowed. She was a perfectly nice woman, available, but he does not fancy her any more. Instead he fancies Minnie Meagles, who is about 20. Meanwhile, Amy Dorrit develops a crush on Mr Clennam, whose intentions towards her were entirely pure and platonic. We believe you, of course we do. Little Dorrit was written about 1857, the last book before Great Expectations. Dickens would have been about the age of Arthur Clennam. So would this have been about the time he was getting rid of the old bag and moving in with the new girlfriend?

Can't help wondering what Arthur Clennam was doing in China all that time. He was there for over twenty years. He was a perfect gentleman of course, but was he celibate all that time? Can't help wondering, either, if he could communicate in Chinese, and had Chinese contacts, why he did not get into the Chinese import-export trade, rather than do something pretty new to him.