How many can!!!

Heather • I just moved from my home town Roanoke va to Charlotte NC. New place new town new look new me
Ok was talking to a friend and was wondering if y'all can give me a hand. My friend said that there is great relationships out there were people have only been with one person married them and are happy. That it was love at first site. 
But I say now a days people don't just have one partner and are married for say 10 and are happy. Maybe 60years a go. Am just saying now a days have many partners is excepted and I don't see no marriage lasting more then 5 years and both partners been happy after so long. So am asking dose anyone or is any ever had sex with only one person and is happily married for say 5 years or more and is between say 20 and 40 years old.