“It would be ungenerous to affect not to know that your self-denial is to be referred to your consideration for her father"
Chapter 10, A Tale of Two Cities.
Just translate parts of the sentence to simpler words, or more-obvious words, or in some cases place-holders, as follows.
• It would be ungenerous → It would be mean
• to affect not to know → to pretend to not know → to pretend [not]
• that your self-denial → that your X
• is to be referred to → is to be attributed to → is because of
• your consideration for her father → your regard for Y
This gives “It would be mean to pretend that your X is [not] because of your regard for Y”. Roughly paraphrased, it says “I know you did X because of Y”.
Edit: I accidentally left out a not. I show it in brackets to indicate that it is moved to a later position in the simplified sentence.