My great-grandfather the cop told this woman she’d been seeing for a while “if I get married, my youngest brother gets out of doing his military service, will you marry me?”
Different set of great-grandparents; they’d met once and absolutely hit it off. “Do they even notice the rest of the world still exists?”-level hit it off. Her mother disagreed with the pairing and destroyed the letters he sent from college. Ten years after first meeting, they ran into each other in the street and the world went away again. I understand there wasn’t so much a proposal as a certainty.
My Dad gave Mom a speech along the lines of “my love for you is infinite, so even if you don’t love me, infinite/2 is still infinite and that means our love is infinite too… will you marry me?”
My brother told his now-wife that, since her parents refused to pay for a necessary part of her education (even though she’d embarked in it at their urging), “if I’m going to pay for someone to prepare her residency entrance exam, I want to be doing so for my wife, not my lives-in-another-town-girlfriend”.
Not sure how my other brother has finally managed to convince the girl he’s been after for about 12 years to say “well, ok…” (no wedding date set, but they’re talking about maybe having children), or whether her biological clock suddenly rang and she decided he looks like he’ll make a decent mate, but apparently it requires him to improve his cooking skills.