So my couples in "Hushabye Prince" and "Damsel in the Red Dress" are opposites in this respect.
At first glance, Kattar and Alicia seem to have a lot in common. Mexican-Americans, raised by single...guardians. Children whose parents went through a divorce. Both rich. I mean they even both have brown skin and long dark hair. But going deeper, they're not very alike.
He shies away from emotions while she's a very affectionate person, who doesn't tend to hide how she's feeling. He was raised rich while she made her own fortune. He's an only child, while so much of her teenage struggle came from trying to care for her little brother. She loves art while he could really care less. He loves action movies while she could really care less.
Where they really meet in the middle is that both of them want to do everything in their power to care for the people they love. But that means something different for each of them. She wants to care for them emotionally, while he wants to care for their physical needs and safety. And trouble is caused when neither one of them are able to do either for the other.
For the "Hushabye Prince" leads
At first glance, Kimberly and Jinwoo have nothing in common.
She's a school teacher, African American, and Melanesian. Just moved to a new city. Very talkative, extroverted, and friendly. Always willing to look at and try anything anyone else is interested in.
Jinwoo has never worked a job, though he's six years older than Kimberly. He's Korean. He's never lived anywhere but this one city, and left it less than five times in his life. He's very quiet, hates loud noises, rarely tries to interact with strangers, and is unwilling to do anything outside of his routine for anyone.
But as the story goes deeper you see that they both have a lot in common. They have trouble interacting with others and are often considered strange. They respond differently to these circumstances. Jinwoo responds to it by focusing on himself and his misery, and her by trying to make everyone like her, but all in all, they have quite a bit in common.
I'm not sure it's really possible to write a story where nobody has anything at all in common, and I don't think people ever fall in love with someone whom they share no commonalities with.