I think you’re forgetting that it’s a real relationship. It’s not that he just picked MM out of the blue to annoy and piss off his family. Harry said that he loved her during the engagement interview. The relationship just isn’t based on a mature or true love like most people would expect for a marriage engagement. Like, AHPF said, “I think it’s pretty twisted and pathetic and based on ego,
attention-seeking, family resentment, and neediness, but I think it’s
real relationship.”