The new girl is, of course, going to have feelings for him which he doesn't reciprocate because he's in love with Dia. Thus if she sees the two of them together she's gonna get mad, lol. He saved her and gave her everything she ever wanted, gave her a reason to live and not curse life, and is likely not going to make it clear that she should throw away any feelings towards him - thus, she'll be like "This woman, how hard has SHE worked for Master Lugh?!"
Prediction squad.