How to know the lover of past lives?

1. They have gold thread in their hands, and their birthdays are seven days apart. They are either eternal enemies or inseparable lovers-

There is a birthmark on my face. That's the mark left by previous lovers, to find yourself in this life.

It's all from novels ...

If you love yourself, you don't have to care if you were a lover in your last life. Both of them really love each other, and sincerity is the most important thing. Besides, what I said is from a novel, and I don't know if it's true or not.