It is a very intelligent idea to not allow anyone to interfere in your romantic life, an outsider most probably have negative effect on your relationship, love needs matured decisions. If you can’t express your own feelings, solve the problems of your own relationship then how can you expect another person to do that? Or think that you will be able to live a life with your lover? A full, complete, life which will face one problem after the other!
Outsiders sometimes cause damages inadvertently, because they are loyal to one side or are not smart enough but quite often they cause damages deliberately, because they don’t like one of the parties, for one reason or other. It can be envy, hidden love or just wicked mind.
Seen too many people who love the part of “Jodi breakers”, that is the scissor that snips the relationships in two pieces to deny their multitude! They can be friends, nosy neighbors or relatives.
If you want lasting relationship tackle your problems yourself.