I'm using marriage encouragement suites to get dorfs to marry:
- Designate a room as the overlapping bedroom of the two subjects.
- Two tile drinks stockpile (with one you typically have that tile occupied by an empty barrel)
- Two tile food stockpile. Both stockpiles are linked to take from their corresponding main stockpiles
- Make a burrow in the suite and assign the subjects to it (often requires fiddling because of cancellation spam when hauled stuff can't be delivered, as well as library stupidity where a serial reader gets cancellation spam when trying to return books).
- Make a tavern zone in the suite. I associate it with the main tavern. This adds another pull factor to get the buggers to actually enter their burrow (apart from food, drink, and sleep).
- Wait (and wait, and wait...) until the subjects are inside the suite. They may escape due to walking away aimlessly after eating/drinking/sleeping, thus extending the delay.
- Once they're both inside, remove the tavern zone until the freeloaders have given up and left, then lock the door.
- Recreate the tavern zone to get the subjects to socialize with each other exclusively.
- Wait for a marriage announcement, but check in on them once in a while to ensure they're not starving or thirsting (if that happens you'll have to let them out, restock the food/drink stockpiles, and herd them back in again).
- You can also check their relations screen to get some idea about progress. The more they get to know each other (assuming it's positive) the higher they climb in that list, eventually becoming lovers.
- Once they're married, remove the tavern zone and leave them to themselves. Once they're sufficiently bored and can't socialize they'll eventually get down to procreation. Spending time next to each other (or in the same tile) and then moving often leaves the female pregnant (I use a script to check for that. Without a script I'd leave them to themselves for a couple of weeks). I've see the female get pregnant while the male is sleeping, but not the other way around (and I'm not meaning the male getting pregnant...).
For more babies, use essentially the same setup, but now in their common bedroom (which may well be the same suite). Pull them into the burrow, lock the doors, disable the tavern zone (if enabled to pull them in), wait until they're performed their duty to the fortress, let them out when (deemed) done.
The adjustments to socializing made in the latest DF version appears to have improved the ability of dorfs to make friends, but I haven't seen any change in the rate of spontaneous marriages.