At the tender age of 105 and 96 two of my starting dwarves finally married, in the 32nd year of Ozornil. (Fort was originally in 40.14, later updated to 40.19) Weirdly this feels like an achievement these days.
Didn't do anything similar to the bunker experiment again, but I kept the redesigned areas, had a massive reduction of available social space and later even the barracks in the same room with increasing idleness for years. + During the last decade a social trap (as small statue garden in a 1-tile wide dead end). At the moment of marriage the dwarves were standing in their adjacent rooms watching each other through a window.
Since I run with very low population cap of 24 earlier, 32 now, I may have lacked some "critical mass" for socialising. The married dwarves were romantically involved for over 30 years and also are the starting dwarves with highest skill gains in conversationalist (now skilled), although the bridegroom is also the grumpiest of my dwarves (dour as a rule) and was a long-term patient of the local stress reduction program.
P.S. A few month later the second marriage, the duchess and the duchess consort. (Interestingly just before both marriages I had freed all social rooms, only meeting hall is active.)