Al Pacino shared a moving tribute to his "Godfather" costar and ex Diane Keaton following her death from pneumonia on Oct. 11 at the age of 79.

Al Pacino reportedly regrets not marrying Diane Keaton after the actress died at 79, ending their chance for reconciliation following their nearly 20-year relationship.

Al Pacino and Diane Keaton had an intense 15-year on-again, off-again affair until they broke things off in 1990 — but a source tells National Enquirer that the Scarface star never stopped loving her and now,

Diane never married but is survived by her two children. Here, we’re looking back at the late actress’ dating history.