Usually in my saves erin Kennedy marries iqbal alvi and becomes the stepmom of vj and miraj. Zelda Mae marries Leighton Sekemoto and thus Sam, Kaylynn, and Parker are stepcousins.

Then eventually the sims that start up as teens end up together:

Any of Parker/Ethan/Michael with any of Holly/River/Bebe. Usually ethan moves in with the bachelors! The most common Pairs are Holly with Ethan, Bebe with Michael, River with Parker.

Lisa ends up with VJ.

Then the kids end up together:

Miraj ends up with Kaylynn, and any of Malcolm/Mortimer ends up with any of Bella/Darlene. Arlo in the canon lore I see him with the Ottomas grandma from 2! Yet if Theres someone he often ends up that I havent mentioned with is Madison VanWatson The Most.

Then the toddlers, Sam and Sandi end up together.

Basically turning pretty much all families related.

The unborn babies Ursine and Keaton, either end up together, or often, Theres a 2nd child of nick and vita, usually a son and Theres a rivals to lovers thing between alto son and ursine daughter.

Jared himself often has 2nd kid with madison vanwatson, and Connor often ends up with Emma Hatch.

Other Sims don’t have much relatives but end up together a lot. Christopher Steel with Jamie Jolina, Xander Clavell with Agnes Crumplebottom (at least often has a child from her), Gobias Koffi with Ayesha Ansari…

A lot of the couples stay together, a lot of them end up with a new child (younger than the unborn ones) not just the altos 2nd child but also landgraabs 2nd, Harts 3rd, bunch 5th, langerak 3rd, 4th, and 5th, Keaton 2nd.

The harts sometimes divorce roughly around the time 2nd child is born! Gus then often ends up or seems to flirt with Yumi and/or Blair. But often they get back together. Clavell divorces are also p common, and buster sometimes dies shortly after his divorce. The Wainwrights also often separate due to nraas unpopular but get together immediately afterwards.

My sims often seem to be aroace, or they crush on Geoffrey or on the black dude from university.

I have Nraas's Story Progression but not the relationships add on. I found in my game that it was way too eager to divorce couples (so I just manually split the couples if the relationship crashes). One thing I have going on that it looks like you have different is that I have it randomly pick people to be attracted to the same gender- usually at about 25%. If that leaves the next generation with people who don't have a romantic interest, then I'll put in some new families with kids of the right gender/orientation. It makes the game a bit focused on 'everyone must get married and have kids!' but having random families dropped into town is something that drives me nuts (as I am compelled to give everyone of them a make over).

Best couple SP ever made: it flagged Bebe Hart and Holly Alto to both be interested in girls. Less than 24 hours in they were dating and got engaged the same day Holly aged up. I was mad when that save got corrupted (it was before I had Nraas Saver so no back-ups).

I often do that too, Theres no common gay or lesbian pairings that I really found, well not in Sunset Valley. but in Hidden Springs i noticed that ella carlisle ends up with Francisca vanderburg. (She also ends up with Sebastian Vanderburg a lot) (another four sims that end up with each other are liam o dourke and the 3 sims from that household i don’t remember the name of) (oooh and francisca with bert alto too!) I had an Hidden Springs where A LOT of babies were born and I think I also partner pollinated the lesbian couples but none of the dryad off Springs ended up green. I was playing a plantsim dryad named Deena Flowerwiew. I deleted the premades and a lot of supernatural sims moved in, and had a lot of kids, then deleted them again, for a third set of sims to move in. The only playables that stayed were Deena and the Kaplans (deaged and renamed Wainwrights, who had four kids, and a grandkid the same age as their fourth kid!) Deena had no kids she had an unicorn and befriended an imaginary friend paparazzi named Tina Albeyta.