Thinking back to when Yus thought to himself how Ran can trust a promise of his but not him himself. Hmm... I think the last few panels gives a great explanation on why she doesn't exactly trust him.
Lol... and this is why Ran still think that he's going to kill her... I agree with other commenters, I'm only reading this because of Ran, having someone say they trust you and won't probe into your business but investigating it behind your back isn't romantic at all...