Read this interesting piece today, from the book The Paradox of Choice
... inevitably, you will encounter people who are younger, better looking, funnier, smarter, or seemingly more understanding and empathetic than your wife or husband. But finding a life partner is not a matter of comparison shopping and "trading up". The only way to find happiness and stability in the presence of seemingly attractive and tempting options is to say, "I'm simply not going there. I've made my decision about a life partner, so this person's empathy or that person's looks really have nothing to do with me. I'm not in the market - end of story."
When you make a decision, try to tell yourself it is nonreversible.