How to Express Your Feelings, 1689

Facepalm Cupid, Andrea Alciato, Emblematum Liber (1534)

Excerpts from The Theatre of Compliments, Or, A Compleat New Academy: 

Expressions of Love and Friendship of Men towards Men.
Sir, I'le repay your love with usury.
Sir, When I contemplate your perfections, I begin to abhor my self for my deficiencies.
Sir, Your great Virtues conquer all hearts as irresistably, as Alexander the Great conquer'd Kingdoms.
Sir, You alone can conduct me to the highest pitch of accidental perfection.
Sir, You have deserv'd more Services from me, than I am ever able to perform.  

Complemental Expressions of Ladies to each other.
Madam, I am forcibly carried away, (I know not by what fate, against the bent of my own Genius).
Madam, You have blasted the harvest of my hopes.
Madam, Nothing shall have power to alien my love from you.
Madam, In the intercourse of affection my love surmounts your's. 

Amorous Expressions of Gentlemen to Ladies, Gentlewomen and Maidens, &c.
Madam, Let the showers of your pity mitigate the fires of my fancy.
Madam, There's a civil assault within me, by which I feel a certain restraint of my own liberty and affections.
Madam, You have no more beauty than will serve to excuse you from being extreamly ugly.
Madam, Your hair negligently dishevell'd, and careless attire, grace forth your beauty; which shines in the midst of so many obstacles, as the Sun in a winter day. 

Expressions of Ladies and Gentlewomen to Gentlemen.
Sir, You are the emblem of terror, and your furious looks are able to consume a woman.
Sir, an ounce of give me, is better than a pound of hear me. 
Sir, I am like a bed of Roses where flowers are mixt with prickles.
Sir, I am not like the Dolphin whom the sound of Musick bringeth to the shore.
Sir, Farewel, you'r grown rude, I dare not hear you further. 

Need a quick sentiment for that greeting card? One of these lines will be perfect for the intercourse of your affection.