We need to love everyone (you need to come to this conclusion yourself through your experience), but devote yourself to only one person (or a man can marry several women, depending on what traditions and your way of life in the place where you live). As far as I understand, marriage is not love, but an agreement from love, in order to become even better, in order to raise a new generation in love and care. It is clear that not everyone thinks in this way, but I think that you need to strive for spiritual purity, for high ideals in everything.