Objection 1. It would seem that there is no natural love or dilection in the angels. For, natural love is contradistinguished from intellectual love, as stated by Dionysius (Div. Nom. iv). But an angel's love is intellectual. Therefore it is not natural.
Objection 2. Further, those who love with natural love are more acted upon than active in themselves; for nothing has control over its own nature. Now the angels are not acted upon, but act of themselves; because they possess free-will, as was shown above (Question 59, Article 3). Consequently there is no natural love in them.
Objection 3. Further, every love is either ordinate or inordinate. Now ordinate love belongs to charity; while inordinate love belongs to wickedness. But neither of these belongs to nature; because charity is above nature, while wickedness is against nature. Therefore there is no natural love in the angels.
On the contrary, Love results from knowledge; for, nothing is loved except it be first known, as Augustine says (De Trin. x, 1,2). But there is natural knowledge in the angels. Therefore there is also natural love.
I answer that, We must necessarily place natural love in the angels. In evidence of this we must bear in mind that what comes first is always sustained in what comes after it. Now nature comes before intellect, because the nature of every subject is its essence. Consequently whatever belongs to nature must be preserved likewise in such subjects as have intellect. But it is common to every nature to have some inclination; and this is its natural appetite or love. This inclination is found to exist differently in different natures; but in each according to its mode. Consequently, in the intellectual nature there is to be found a natural inclination coming from the will; in the sensitive nature, according to the sensitive appetite; but in a nature devoid of knowledge, only according to the tendency of the nature to something. Therefore, since an angel is an intellectual nature, there must be a natural love in his will.
Reply to Objection 1. Intellectual love is contradistinguished from that natural love, which is merely natural, in so far as it belongs to a nature which has not likewise the perfection of either sense or intellect.
Reply to Objection 2. All things in the world are moved to act by something else except the First Agent, Who acts in such a manner that He is in no way moved to act by another; and in Whom nature and will are the same. So there is nothing unfitting in an angel being moved to act in so far as such natural inclination is implanted in him by the Author of his nature. Yet he is not so moved to act that he does not act himself, because he has free-will.
Reply to Objection 3. As natural knowledge is always true, so is natural love well regulated; because natural love is nothing else than the inclination implanted in nature by its Author. To say that a natural inclination is not well regulated, is to derogate from the Author of nature. Yet the rectitude of natural love is different from the rectitude of charity and virtue: because the one rectitude perfects the other; even so the truth of natural knowledge is of one kind, and the truth of infused or acquired knowledge is of another.
Source: Summa Theologica (New Advent)