Kaia lives alone and does not want a nesting partner. She is fulfilled by her relationships with Ursula and Lari, who are a nesting couple that Kaia visits regularly.
Nedbert has a long term partner who lives in another city, and also enjoys casually dating others. He avoids entanglements because he wants the freedom to make big decisions based on what would suit him best, without having to factor partners into the equation.
Jan needs lots of time to themself, and living alone is the best way to get that need met. They have a healthy dynamic with their submissive, who respect their need for independence.