They are at the Romance Festival. I'm not where I can add photos but you'll usually see them standing behind the fountains where you drink the pink tea. You can ask for advice and find out your romantic destiny. I like doing that whenever I send a sim to that festival.
Certain sims do seem to subtly have a harder time finding love than others though I am on team attraction system and romance overhaul. If the sim gets a bad fortune then they start crying. I think the first love guru is Raj's mother but then the game automatically generates a new one.