I knew… or I thought I knew that a part of her still loved me,

that he is beginning to doubt she loves him.
which is why she hadn’t accepted Luthor’s proposal in the first place.
I think he is right on why she didn't accept, but for the wrong reasons. She knew how much it would tare Clark up if she accepted without him knowing what was up. However, they messed up the talking to eachother session, and so now he is being torn up just like she wanted to avoid.
I thought that’s what she wanted from me, a better offer,” Jerome confessed,
I guess this almost makes sense, but not really.
“Well, that respect is gone now.” He shook his head.
“No, that’s not right. She said she wanted my advice about Luthor’s proposal. See! This is why I thought she wanted me to propose.”
Martha:When women say "advice" they mean "advice" not action.
Undoubtedly, the word ‘advice’ had a different meaning in Jerome’s home universe, Martha surmised.
It would help if she said this aloud.
“So, your advice was ‘don’t marry him, marry me’?” Jonathan said softly. “Son…”
The way Jonathan describes it, it does sound like advice.
Jerome raised his hand. “I know. I know. The worst possible thing I could have said, apparently.”
Technically not. It would have been worse to say "Go get in bed with the devil, I don't care."