Neela, I believe infidelity is preventable, if the person who is considering it chooses not to do it !! However certainly you, as the "innocent" party so to speak (I am using that term loosely!) cannot prevent your partner from being unfaithful. Please do not place such a burden upon yourself. Yes, there are actions you may take to strengthen your relationship in general, however; infidelity is a choice that your partner must own entirely. There is nothing saying a man or woman who is unhappy in a relationship must cheat; if they are unhappy, they have the option to end the relationship in an honest and mature manner.