C´mon!! seriosly???
I think that way of thinking... "Just one for life time" is really romantic and cool... but I guess that everyone is unique. For me, theres no need to marriage, and if you are in a relationship and you really love that person, then DO IT!
and in case you go and meet TONS of lovers... then I sugest you to Let it be... dont rush the magic... but if the Magic Moment Happen... dont you ever dare to regret it.
3AO7-LOVE
(my perspective of Love as a ying-yang)