Every love contains fear and grief: fear of it being destroyed, and grief if it is. Likewise conjugial love, but its fear and grief are called zeal and jealousy. The reason why, in the case of couples who dearly love each other that zeal is justified and has sound reason behind it, is that it is at the same time fear of the loss of everlasting happiness, not only one's own, but one's partner's too, and because it is a defence against adultery.

As regards the first point, that it is a justified fear of losing one's own and one's partner's everlasting happiness, this is the consequence of everything which has so far been reported about truly conjugial love, and of the fact that this love is the source of the blessedness of their souls, the cheerfulness of their minds, the delights of their hearts and the pleasure of their bodies. Since these remain with them for ever, it is a fear for the everlasting happiness of them both. It is obvious that this zeal is a justified defence against adultery. As a result it is like a fire blazing out against any infringement, and protecting itself against it. It is evident that one who dearly loves his wife is also jealous, but with justification and reasonably if this accords with the man's wisdom.