St Valentine is one of a small band of martyrs (along with St Thomas More) who died not least in the defence of the Christian conception of marriage. Accordingly, a saint to whom we might particularly ask help for those who are attempting to defend the institution once again today.
Martyred during the reign of Claudius II, the saint was arrested and imprisoned upon being caught marrying Christian couples and otherwise aiding Christians who were at the time being persecuted by Claudius in Rome.
Here is a reading previously used in the Office for his feast, from St Augustine:
The illustrious day whereon the blessed Martyr Valentin conquered, doth this day come round to us again and as the Church doth rejoice with him in his glory, so doth she set before us his footsteps to be followed. For if we suffer, we shall also reign with him. In his glorious battle we have two things chiefly to consider the hardened cruelty of the tormentor, and the unconquered patience of the Martyr the cruelty of the tormentor, that we may abhor it; the patience of the Martyr, that we may imitate it. Hear what the Psalmist saith, complaining against sin: "Fret not thyself because of the evil-doers, for they shall soon dry up like the grass." But touching the patience which is to be shown against the evil-doers, hear the word wherewith the Apostle moveth us Ye have need of patience, that ye may receive the promise.