In the end, whether married or not, a couple that separates can either do it amicably or not. You can ruin your partner's life without being married. Like wise, a divorce doesn't need to ruin anybody's life.
What you want is for any partner you get, to be happy to leave whenever you don't want them around anymore. That's is not a problem of marriage. That's a problem of human psychology.
> The current legal form of marriage formalizes love in a contract that doesn't take into account the fact that love can disappears one day for no reason
Maybe marriage takes more facts into account than your "reinvented marriage". I've been married for nearly a decade and a half and have had love disappear one day, only to reappear a couple of days later. If all it took was to pack my bags and leave I might had done it.