Here's what I think about people, regardless of whether is it male or female, who cheat on their partner or has a sudden change of heart. Firstly, I have to say I'm
NOT condoning such acts. I'm just here to try to give my own opinion on why I think this happens and why maybe we shouldn't be putting all the blame on the other party.
Okay, let's go. Here's what I think, my own personal opinion. You can agree, you can also disagree.
REASON FOR HAVING MORE THAN ONE BOYFRIEND/GIRLFRIEND AT ANY ONE TIME:Reason being, we are human beings and we are animals too after all. What's the purpose of an animal's life? Isn't it to reproduce? Now let me make it clear first, I'm saying we are animals, but we are extremely CLEVER animals.
So why some people have more than one boyfriend/girlfriend at the same time? Reason is simple. It's all in our genes, nothing can change that. We simply want to reproduce. Just look at other animals in the wild. Take lions for example. A male lion is, most of the time, surrounded by a few females. Of course, I'm not saying humans are comparable to lions. I'm just saying when someone has the urge to have more than one boyfriend/girlfriend, you can't say he/she is unfaithful. Like I've said, I think this is all in the genes. It just depends on whether can you suppress this feeling or not.
REASON FOR A SUDDEN CHANGE OF HEART AND FALLING IN LOVE FOR SOMEONE ELSE:What makes humans fall in love? Pheromones is to be blamed I would believe. Once again, this feeling of falling in love with someone else when you are already attached can still be controlled. Some people simply succumb to it while some can resist the temptation of it.
So why is "I will love you till the day I die" untrue? Because when you meet someone else who produces pheromones that attracts you, you are highly likely to fall in love with him/her if you are not careful.
So once again, if your partner decides to dump you for someone else, it is perfectly understandable. You may feel sad and utterly useless, but there isn't a choice. We have our genes and ancestors
and Pheromones to thank for. Just move on in life and find another partner and hopefully you'll find one that truly loves you and he/she is able to control his/her feeling so that he/she won't fall in love with someone else.
Once again let me make myself clear. I'm not writing all these to help the unfaithful people out there. I'm just trying to provide a plausible explanantion to why this may happen. Whether or not one goes astray is all up to his/her level of self-discipline.
I'm just trying to say those two scenarios mentioned above will definitely have a chance to occur if the partner doesn't have enough self-discipline.
Don't move to Aunt Agony please, I'm not in any agony.

And don't flame me. I'm just saying out my own opinion.

Edit: In bold.