No matter what they do or say, I will always love them.
Unconditional love has no place in romantic love. They shouldn't even be sharing the same words.
Romantic love is absurdly conditional. We need a different word. The word "lust" is also a temporary state, even with new couples.
Music, romantic movies and shows like "The Bachelor", have warped our cultural ideas around relationships.
However, sometimes media can explain it perfectly:
"Listen Morty, I hate to break it to you, but what people calls 'love' is just a chemical reaction that compels animals to breed. It hits hard, Morty, then it slowly fades, leaving you stranded in a failing marriage. I did it. Your parents are gonna do it. Break the cycle, Morty. Rise above. Focus on science."