How can you be ''the love of their life'' if you're gonna dump them anyways?

I've heard these known phrases too many times.
''You're the love of my life''
''You're my soulmate''
''We're meant to be forever''

You're going to dump them anyways so what was all that enery, talk and time spend for? It doesn't make sense to be someone's ''soulmate'' but only be their temporarily girlfriend/boyfriend that can be replaced any moment. There is nothing holding you together without kids... nothing. Total waste of time. Too much for nothing.
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If you can dump them and then actually have kids with someone else then that person was NEVER the love of your life.
How can you be ''the love of their life'' if you're gonna dump them anyways?
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