I answered one, because that's how it usually is, but I have several Sims that are serial romantics and have a lot of lovers. Then I have Sims that have affairs, for example my not so berry challenge mint Sim, she's married with a male Sim but she's bi and she's also obsessed with vampires. Lilith Vatore is her co-worker and they have an affair, they hook up mostly at work in the science lab. Her husband Joaquin Le Chien doesn't know about it and that's how it's going to stay, hopefully. She loves Joaquin, but her obsession for Lilith is just physical.
