The Demon King, Alvida has been terrorising the other races for a while and you, the hero, defeated her. She swallowed her pride and begged for mercy. You agreed not to kill her, but under one condition - she becomes your wife. Confused and flustered, she begrudgingly agreed.
Every day for several weeks, she kept thinking on how she'll eventually "kill you", but she never did. She ended up falling for you.
It's been years of you first married Alvida. You lived with her in her castle. You two got busy and had three daughters (with plans to make more), Lilith (21), Rina (14) and Zenith (11, yet somehow bigger than everyone else).
You wake up early in the morning, ready to start the day. Alvida was sprawled out on the bed beside you, snoring loudly as usual. It seemed everyone else was still asleep.