Acaramelados – lovey dovey
Al Gato viejo, ratón tierno – old geezers like sweet young things
Amor – love
Amor a primera vista – love at first sight
Amor juvenil – puppy love
Amorío – a love affair
Anular – to annul
Adventura amorosa – a love affair
Adventura extramarital – an extramarital affair
Asaltacunas –cradle robber
Comprometerse – to become engaged
Cupidito – Cupid
Dar vuelta – to cheat on one’s mat (Costa Rica)
Deshojando la margarita – “Does she love me, she loves me not , etc. ?
Dejar plantado – to stand someone up
Descorazonado – heartbroken
Desenamorarse – to fall out of love
Enamorarse – to fall in love
Echar el caballo – to make a pass at or to hit on (Costa Rica)
Echar el cuento –  to make a pass at or to hit on (Costa Rica)
Echar los perros – make a pass at or to hit on (Costa Rica)
Echar el ruco – make a pass at or to hit on (Costa Rica)
Echarse la soga al cuello – to get married
Enculado – head over heels in love (Costa Rica/vulgar)
Encularse – to fall in love (vulgar)
Estar loco or loca por alguien – to be crazy about someone
Gallina vieja hace buen caldo – an old hen makes a good broth
Hacer el amor –to make love
Juntados – to live together
Matricidio – marriage (matricide)
Media naranja – one’s other half
Morirse por alguien – to be dying for someone
No hay amor sin dolor – no love without pain
No hay rosa sin espina – same as the last one
No hay amor sin interés – same as the last one
Perdidamente enamorado – lost in love
Pepeado – head over heels in love (Costa Rica)
Picaflor – playboy
Ponerle los cuernos – to cheat on a man
Romper el corazón – to break someone’s heart
Sonarle las campanas de la iglesia a alguien – someone is going to get married
Templado – horney
Tener algo con alguien – to a have a relationship with someone
Tener celos – to be jealous
Tórtolos – love birds
Traicionar – to betray
Volar rabo – to make love in Costa Rica (vulgar)

Humorous expressions about love:

Amor con amor se paga – have to reciprocite in love
Antes que te cases mira que haces – look before you leap (marriage)
Dejar como novia del pueblo – to stand someone up
Casarse por detrás de la iglesia – to elope
Como en el amor y en la guerra, todo se vale – all is fair in love and war
Cuando de los cincuenta pases, no te cases – don’t get married after 50
El amor es ciego  pero el matrimonio abre los ojos – love is blind but marriage opens the eyes
El que casa por todo pasa – he who marries goes through a lot
Ir a la guerra ni casar no se ha de aconsejar – don’t get married or go to war
Ni con ellas sin ellas – can’t live with them or without them