So it would prove, by your definition, that the Baby groot hug baby yoda I can’t breathe shirt walkaway partner never loved the one left behind. Think differently, think of all those chemical signals being deep wisdom of evolution speaking to us. Nor are they all-powerful. The release of some of them is due to our interactions as conscious beings. Even if you do care about your partner more than about yourself, it is still your responsibility to protect yourself from harm. If you are deeply in love with a person who is harmful to you, you still need to take measures to minimize the damage you will suffer. This can include breaking ties, just because it’s the right thing to do.
Or look at it this Baby groot hug baby yoda I can’t breathe shirt, is it scary to find a woman beautiful or a man handsome? Those reactions are hardwired too to survival and fertility traits. Is it scary to have instincts that keep you safe from falling, cause you to snatch your hand back from a burn, or any of a hundred other reflex actions? Why do you expect your greedy genes to take a chance on this really important task while being so careful to keep you alive? Most people who are cheated on are not so deeply in love that they care about their partner more than they care about themselves. It is only good that someone likes you when you like them too. If you love someone and they love you back, you create heaven on Earth.