This is my personal belief and Im aware others will have theirs.
If giving an opinion try actually give a reason why you feel a certain way. Cursing or complaing about another's opinion without explaining yours is pointless.
I will start with this. The idea that you cannot love more than one person romantically is heavily flawed. People say that if you love this person you clearly don't love the other. This couldn't be more wrong. We prove this wrong each day of our lives. We can love our mom and our dad. We can love our brother and sister. We can love our dog or cat. We can love our friends. That already can add up to more than 10 people.
Now is this love different or lesser. Yes... But only to an extent. Romantic love and family love is different. Yet very similar. You care about this person. You wish no harm to come to them. You would protect them or give your life for there's. I feel that way about my family and some friends. Now people will contradict this by saying if you love more than one person romantically. You clearly don't care if you hurt the other person you loves feelings... Why would that ever be the case. You love both. You don't want harm to come to either. Just cause I love my dad doesn't mean I want my mom to get hurt.
I am in no way. Shape or form defending cheating. I find cheating a horrible thing and the person who cheats deserves the consequences. The issue I take is with telling or rather yelling at this person that they never loved their significant other. How does them falling for another impact the love they have for the original. Of course there times love lessens or it wasn't true love to begin with. But people have always been able to love more than one person. So hating on someone who has fallen trap to this instinct is pathetic and pretty judgmental.
Have we not had crushes that come and go. Do we stop finding others attractive once we with the person we love. Of course not. Which is why I believe in society it's seen as acceptable to be monogamous. But polygamous... That's just horrible. When in matter of fact. Our brains are wired to be polygamous. To have different levels of love for different people or things. I say again. This doesn't make cheating or lying okay. But it makes it so that people should get off their high horse when insulting someone who may of fallen for another.
They have a big decision to make. But that doesn't mean they hate or disliked the original person they loved. Assuming that is extremely cruel and unfair. Cheating is cruel and unfair. But that's my point. We may accept monogamy but in our hearts I believe we all have a level of polygamy inside us.