My Family Is Too Precious to Let Go

After suddenly finding herself in the world of a novel, an ordinary side character plans to live quietly and stay out of the way. Instead, she ends up marrying the father of the female lead. She intends to maintain a reasonable marriage, make her young stepdaughter happy, and divorce once everything is settled. But the girl is irresistibly adorable, and her husband is far too handsome, putting her carefully arranged plans to divorce in doubt.