Kaelen chooses Ivy, not out of love, but out of a need for an heir or to satisfy his own dark desires.
He initially views Ivy as a means to an end but becomes consumed by his need to keep her safe and happy. Ivy (The Human) Traits: Resilient, defiant, and compassionate. Property of the Dark Elf by Celeste King
If you are looking for more specifics, I can help if you tell me: Kaelen chooses Ivy, not out of love, but
Features kidnapping, power imbalances, and dub-con (dubious consent) elements typical of "dark" romance. Kaelen chooses Ivy