It is a mistake for Tom Robinson to admit any kind of feelings for Mayella. He should have left out his compassion for her. This gives him a motive to sexually assault Mayella. Of course, Tom was only admitting that he had compassion or pity for Mayella, but this admission puts Tom in a bad light. Now, it appears that he has feelings for Mayella. This is not something Tom should have admitted.
No doubt, the jury is wondering why Tom would have any sentiments whatsoever for Mayella. Why did he feel sorry for her? Who is she to him? Why does he know she has a hard time with the chores around the house? Tom knows too much about Mayella. This puts him in a negative position. Tom passed by Mayella's house each day. He knew she had a difficult time with the chores around the house. Obviously, Tom had had a conversation with Mayella before:
Because he saw she was left alone to maintain the household without any help from her family, he often performed small chores for her. During his testimony, he relates that he felt sorry for the girl. This remark affronts the white men in the jury, who see it as evidence that he is overreaching his social station.
Tom would have been better off to never have admitted any kind of emotions or feelings for Mayella Ewell.