As an INFJ, I got:
“I trust you with my heart.”
INFJs are both overwhelmingly caring and notoriously skeptical of others – which results in them being highly selective about whom they place their trust in. For this type to fall fully in love, they need to feel completely comfortable with their partner – and to believe that they are someone they could fit with longterm. If an INFJ says ‘I love you,’ they are letting you know that they trust you – and that they see a future alongside you.