Unplayed sim randomly develops romance bar with played sims + own family members

I'm fairly certain at least some of this is a bug, but I'm not entirely sure if all of it is. 

Basically, I was playing with a family and I got two notifications, one for each of my YA sims, saying "romantic satisfaction has begun with Marcel Price". I had never interacted with Marcel Price on this save so I thought that was odd, but I don't know all the features of Royalty and Legacy so I thought maybe he autonomously wished for something and it went wrong.

So I focused the camera on Marcel who was in the world, and saw him kissing Keven Puri. Which is a sim that I am pretty sure is supposed to be like a foster child of Marcel's, so I think something weird has happened. Went to manage worlds to see if I can learn anything from going into Marcel's household- see if he has any moodlets or anything that would explain, but I found this:  

He has the same relationship with all the sims he knows, including his children. Almost full romance, red bar halfway on friendship. Only moodlets are "Feeling Great" and "Enchanting Coastline" (From R&L). There doesn't seem to be any unusual activity in his milestones - except that it doesn't have the "fell in love" milestones you usually get when romantic satisfaction begins. 

This is WEIRD. I was vaguely interested in seeing where the storyline might go when I thought it was a feature, but considering the romance bars with his children I'm now not sure if it's a feature or a bug or a combination of the two. 

PC, all packs (except some kits) owned, no mods or cc ever used on this save file. 

I also want to note I've been seeing way more bugs than usual since the R&L release. Most aren't a huge deal, can be fixed with resets or restarting the game, but it's a bit of a nuisance how often things are going wrong.