I've heard several people say, "You're the love of my life," and eventually, for some reason, that love of their life ends. Then another person comes along and repeats the phrase, and so on. Perhaps this phrase should be changed to, for example, "You're just another love in my life."
LOL you are right, these phrases are too easily said. It's my belief you know it after years of being together through the hardships. It's easy if it's fun. The yes in .... is another one. Thankfully, I never heard anyone say it and I never had to.