When you are in a relationship for a long time with someone and both are not so Naive, you tend to take the other person at ease.
We humans like to chase. We like to explore our limits and experiment with new things. We are not satisfied with what we have and tend to try out new things.
The reason why third person’s involvements ruin a relationship is boredom. We are bored and we try out new things. We lose interest in our already existing one and these new things give us thrills and feelings which are lost. We want to start afresh with someone new and not to be judged and already known about with the existing one. When we are with the same person for a long time we take each other for granted and we know they can be manipulated and they will forgive us whatever the reason be.
Which is a disgrace.
Here comes the concept of trust and loyalty.
A relationship is built on the general ground of trust and mutual understanding. If a third person is getting involved then it is not the fault of the third one, your loyalty should be questioned.
You have given the third person enough right and space to shatter the foundation of your relationship. You have reasons to lose(your love) whereas third person has nothing to lose and is just enjoying the attention and importance received more than your partner.
Instead of letting a third person putting hindrance in your relationship, it is better to talk with your partner, understand where you two are going wrong and take mutual decision. If things can be sorted out, it is well and good. If you have parted a long way and it cannot be worked out then come out of the relationship in a much venerate manner.
