The Base for Mad Love

What is the base for a normal relationship, the one that isn't peppered with drama or anything on the verge of reason and common sense? This base prompts such notions as mutual respect, understanding, trust, honesty, sobriety, decency, smooth 'flow' of a relationship without too many keen angles which hurt the two people in a couple and make them bleed (in a figurative way). In other words, normal relationship and its base differ from that of the mad love.
While the base for mad love is in the majority of cases sensual connection. This factor and realization of the fact that this chemically physical connection is too strong to let go makes the relationship go on and often even last longer than something trivially casual.
The two people within the acute boundaries of mad love may have absolutely nothing in common, there may be a precipice between their age markers, between their outlooks, their morals and general views on things.
In other words, the base for mad love is purely physical which contributes to establishing of a more or less strong emotional contact between the two people. However, the total lack of common spirituality, something more than mind-blowing sensations, something like romance or quiet trust, their impulsive character which sometimes doesn't prompt any compromises, all this makes the couple based on mad love fall apart eventually.