It's inevitable: Sooner or later, the intense passion that characterized the beginning of the relationship will start to dwindle. Little things you once thought cute about your significant become a source of annoyance. The end of the so-called honeymoon phase ushers in reality, when both people's flaws are in full view and you actually have to put in effort to sustain your partnership. Gone are the days when love notes and makeout sessions had you on cloud nine and little else mattered. Once couples have to reckon with this natural phase of an aging relationship, some -- especially those who have been together a long time -- quickly panic, taking this to mean the relationship is on its last legs. But this isn't always the case. A relationship is only as strong as the effort BOTH partners put into it. This means that, yes, a 10-year-old relationship could actually be healthier than a 10-month-old one. So what exactly is the secret sauce to keeping a relationship e...