Charles Hodge on Ephesians 5:29

V. 29. Conjugal love, therefore, is as much a dictate of nature as self-love; and it is just as unnatural for a man to hate his wife, as it would be for him to hate himself, or his own body. A man may have a body which does not altogether suit him. Ile may wish it were handsomer, healthier, stronger, or more active. Still it is his body, it is himself; and he nourisheth it and cherishes it as tenderly as though it were the best and loveliest man ever had. So a man may have a wife whom he could wish to be better, or more beautiful, or more agreeable; still she is his wife, and by the constitution of nature and ordinance of God, a part of himself. In neglecting or ill-using her he violates the laws of nature as well as the law of God. It is thus Paul presents the matter. If the husband and wife are one flesh, the husband must love his wife, "for no man ever yet hated his own flesh, but nourisheth and cherisheth it." Ἐκτρέφειν is properly to nourish up), to train up by nurture, as a parent a child; comp. 6, 4. Θάλπειν is, to warm m, to cherish as a mother does an infant in her bosom. Both terms express tenderness and solicitude, and therefore both are suited to express the care with which every man provides for the wants and comfort of his own body.

Καθὼς καὶ, even as also, Χριστὸς τὴν ἐκκλησίαν, Christ the church, i. e. Christ also nourishes and cherishes the church as a man does his own body. The relation between a man and his wife is analogous to that between a man and his own body. And the relation between Christ and his church is analogous to that between a husband and his wife; therefore Christ nourishes and cherishes the church as man does his own body.