Oh, this I love! I love the dance Millicent and Dudley do around one another, and I love the ways they both say to hell with parental expectations.
I also love that Dudley doesn't want to "interfere with Harry's happiness"--it seems a bit like insecurity/fear of rejection, too. I'm glad he got over his fear of rejection in order to try something with Millicent! She sounds like my kind of woman :)