I don't know.
I just ran into a serious glitch. I was testing the attractive system which I can't figure out. Artie met someone, married them and they never moved in. Artie's wife kept her name, her house, her roommates. I was still only playing Artie.
Wondering if it was a bug I tried it again in an unaltered Lucky Palms with Donovan Steel and Marisol Loera. Same thing. Both were private weddings at some place random.
The attraction system seems to take all sorts of things into account looking at the data. I found these in Relationship_0x5da0f93630ce52d4
Base random attraction value 0 - 100 (seems to be a random number applied for an initial score)
Bonus or penalty of 30 for matching or opposing traits
Bonus of 1 per career level
Bonus of 0.5 per skill level
Bonus of 30 for matching occult
Bonus of 2 per celebrity level
Bonus of 30 for compatible sign
There's also a bonus if one of these buffs is present, FreshClothing, MintyBreath, NiceNails, SmoothSkin, SqueakyClean, VeryFreshClothing, EyeCandy, Stylin, StylinPermanent, Suntanned
And of course family funds make you more attractive too, so basically it seems to be if you have a good job lots of money and clean laundry you're sorted.
The attraction threshold is 101, so hit that score or above and the two sims will be attracted.
Last night I started a test game of this patch, put my self sim in as a teen first, not seen it work on teens as yet so maybe it's just for adults.
Subject 1: Dallas Shallow
She talked to Dallas her usual husband, they flirted like they always do but no attraction thing, they just have music and sometimes zodiac in common, in this game they were compatible. It may not have fired any attraction thing but it didn't stop them being all over each other as usual.
Subject 2: Trigger Broke
With Trigger she has clumsy, music and cookies in common, this time no zodiac. Nothing happened there either even though on paper he seems more suited.
So with that not doing anything I started again and put my YA self sim in and sent her to see somebody I knew should work.
Subject 3: Sherman Bagley
On paper she is a perfect match for Sherman but they have never been anything but best friends. They are both neat and friendly, both like cookies and blue and in this test had matching zodiac.
She said hello and they both got a thought bubble of each other with flying hearts floating off, then a pop up of Sherman saying "we have a lot in common I'd like to get to know you better"
She also got a +10 moodlet when near him.
I found nothing in the xml about favourites so I'm guessing it just took the traits and zodiac into account, plus the fact he is rich. One thing that didn't happen which pleased me was they didn't then start flirting, can you imagine the chaos if this caused instant autonomous flirting between two attracted sims.
There is another xml that deals with the gift giving and love letters, it seems if a sim is attracted to you there is a chance they will call and ask you on a date but thankfully if you turn them down 3 times they will stop else that could also get a bit annoying.