Men can very easily transfer their love from one woman to another.
They seldom grief long when their partner dies, goes away or is otherwise unavailable. They love what women are doing or providing for them. They love women, because they feel women love them and they love them back for it.
Some people might think this kind of love is shallow. But it is not. It is not the person they love but the giver of love they love. This love can be enduring – till death do us part – but it also has survival value, because it is easily transferable.
Men’s love is more a loyalty program. A lot of women died during childbirth and men must have had the ability to find a new partner quickly to look after their earlier brood. If the man was able to love his new wife and his new wife felt that love and was able to reciprocate then they could live happily ever after.