In my opinion, there are a couple of absolutes. 1). You need to have your sexual desires fulfilled by your partner. 2). You need to have a common "life project" that you share an active interest in. 3). You need to have separate spaces of existence available. Number one is number one. If you have fantasies and cravings that you do not share with your partner, your relationship will inevitably break, in whole or in part, sooner or later. This is THE major issue. Not having a sexually satisfying relationship is worse than having no relationship at all. Intimacy is king. Sharing your body and soul begins in bed. Number two simply means that you have a common goal that you work towards, that you take an active interest in and feed off eachother with. The most common "project" like this is of course to make a family and raise kids - but even without that you will still need *something* that unite you outside of the bedchamber. Business, studies, whatever. Number three is about withdrawal. No matter how close you are and no matter how tight it is, there will be moments when your mood shifts and you feel alienated and needing to be alone, just wanting to be silent and ponder whatever weirdness it is that occupies your mind. This is when you need to have *faith* in eachother and allow it to happen. People are weird. Deal with it. Tomorrow's another day. If you have 1, 2 and 3 checked and roger'd, your relationship stands a fair chance of success.