Problem is, I cannot take a single person and perform such test yet 10 million thats why I was looking for some solid stats or research/paper.

Maybe you don't hear. My grandparents were together since about 16 and my grandmother passed away 12 years ago. And I never seen couple more in love, including my grandma having tatoo of his name on her chest, something unheard of and frown upon back in the days. And my grandfather is turning 94 this summer.