Not with a Half-blood, redux (гет)

(This is a revised version of Not With a Half-blood!)
A post-war Harry and Daphne betrothal, but without magical contracts, ancient betrothal contracts or... Harry being unable to get out of it. Daphne Greengrass at a ministry party tells that famous half-blood about her imminent engagement and marriage to the new head of the house of Black, Draco Malfoy. Harry is confused.
The only reason he would marry her is so he doesn't have to declare her unacceptable. Some sort of very dated old pureblood custom.
Oh, she is fairly pretty, if rather worried about being declared unacceptable.
Which she knows Harry Potter would; he hates Slytherins, purebloods, and she isn't as pretty as Ginny Weasley.
A saving-people-thing ensues.
This version is for people that want to see Harry's inner thoughts, such as they are. It might not make him look mysterious, noble or wise, but he is, after all only twenty.