You betraying it, sinful if you are in the position of the betrayed person. According to experts there are only two types of betrayal and two different ways to cope with each.
The first type of betrayal in the couple is the one by which the traitor tries to fill the gaps that he offers the relationship with the neighbor. For this reason it opens to other experiences, but without investing in them sentimental side.
This means that the only way to fight this kind of betrayal in the couple is conversation and filling gossip that may have the couple relationship.
While the second type of betrayal is somewhat deeper and comes precisely when one of the couple's partners can not or will forget to invest as much as possible in relationships. That is why the traitor requires a different experience, after which he invests the sentimental side.
The only way to withstand this kind of betrayal is to couple therapy, in order not to reach the separation that in such a situation becomes inevitable sooner or later.