My parents had a long and happy marraige, raising 8 children to healthy and productive lives, for well over 50 years til Dad passed away. The In-Laws too had a long, happy marriage (60 years) til Dad-In-Law passed.
My eldest sister is married over 40 years now. Ours is 34 years this year. Older brother 28 years. Other siblings are also married, long term.
My own kids are married or partnered up with long term partners/spouses.
Successful relationships take effort. Like a post I saw on Social Media said "When a couple was asked how they made their marriage last 60 years the reply was "We came from a time when if something was broke, you fixed it"," That is how it works, rather than give up at the first hurdle.