Who said so? Of course eating at meals is a holy and sacred occasion.
Prayer before meals:
Bless us Oh Lord, and these thy gifts, which we are about to receive, from thy bounty, through Christ, Our Lord. Amen.
Prayer after meals:
We give thanks for all your gifts, almighty God, who lives and reigns forever. May the souls of the faithful departed, through the mercy of God, rest in peace. Amen.
I don;t deny that sex between husband and wife is holy, but why would it be significantly more so than eating? If sex between couples is significantly more sacred, then what is the common prayer which is said before and after? Notice, that there is are well-known prayers, which are known by all educated Catholics to be said before and after eating.