A couple should probably make sure they can successfully cohabitate before deciding to spend the rest of their lives together. However, there's no scientific evidence that premarital cohabitation improves marriage quality or reduces divorce rates.

Living Together Before Marriage

Research indicates that measured physiological signs of arousal are self-reported more accurately in men than in women. Also, straight and lesbian women show physiological signs of arousal when watching sexual videos regardless of who was with whom. The gap between the arousal that women report and the arousal they feel, is theorized to be a consequence of societal repression.

 The Libido Of Men And Women

There's no evidence that differences lead to greater attraction or improved relationship outcomes. Similarity does predict attraction and relationship success.

Attraction Between Opposites 

The general consensus amongst social scientists is that children cause a drop in marital and relationship satisfaction.Moreover, marital satisfaction usually doesn't begin to recover until children "leave the nest". Raising kids is certainly worthwhile, but that doesn't change the fact that it's immensely difficult even with careful planning.

Arrival Of Children

Popular culture perpetuates a lot of poor information about intimate relationships. The systematic disinformation can, and does, lead people astray, and not just into hilariously awkward situations (see almost any romantic comedy), but into genuine misery.