Why do people want to tear down happiness?

I neither usually find myself blogging two days in a row nor writing about people that hate on others but this time I decided to take special notice about something. I was having a talk with my boyfriend, which I do love very much and he was telling me about something that happened the other night. Normally I don't address negativity in this fashion but I wanted to take this time and use his experience as an example for several positive aspects.

He was in the presence of his friends and one of his supposedly good friends started to disrespectfully talk about me. Whether what this person said was true or not, if you are somebody's friend, you should not be degrading your friend's relationship and partner. When this person started to say insulting and disrespectful things about me, my partner asked this person to stop. This person basically challenged my partner and said "What will you do if I don't?"  My partner kindly asked him to leave and locked the door.

I have been in this same situation and what we are talking about here is basic relationship common sense. The example I want to bring to light is the fact you have someone that wants to tear down what another person and I have tried to build at every turn. Obviously jealousy comes into play and not jealousy of me. This person is obviously jealous of the fact that someone stood up for me with heart and I would do the same with no questions asked. So basically, I was chosen over his friend and I am sure that this person will be back to even out heart with hate as he has continuously done over the years. The question is not even why someone would do that because that answer should be apparent. My question is, why is this not done when I am there?  It is easiest for outside forces to throw your relationship off when two people aren't standing together in a relational and physical sense.

I write a relationship column, so I want to come with relationship advice from life experience and the books of knowledge. A relationship is a package deal. If you have toxic friends continuously trying to unravel the package, eventually you will have to let them go. We are human and when we slip up in our relationships, that toxicity will seep in to corrode what you worked for. It is like a curse. A curse takes years for it to become full strength before it does real damage and that is the same with these type of people. Yes, what I am saying is that as humans we are all susceptible to the curse. No one is different because we all will become vulnerable and the curse finds it way in after a period of being introduced to the same evil.

So if you have people in your life trying to make your relationship harder for you because they are not happy in their own life, just close and lock the door on them. Hard as it maybe, it is the best and I mean the best thing to do if you value your holy trinity. You, your partner and your relationship.