Rosalba, her host and his daughter in law tell their stories - the background is outlined.

LET'S SEE AN EXAMPLE

Rosalba is still in Venice, where she met a man named Fernando. She told him nothing about her family. She is staying by him. One night, while Fernando is not at home, someone rings the doorbell. It’s a girl, together with a child. Rosalba thinks that the child is Fernando’s son. The girl tells her about her difficult past: she was neglected and abandoned by her partner (the father of the child). Rosalba starts thinking that Fernando is a crook, hence she tails him. Actually, Fernando is no the father, but the grandfather of the child and the person who committed so many mistakes is Alan, Fernando’s son. 

Bread and Tulips, S. Soldini, 2000, Istituto Luce (01:04:00 - 01-11:00).

How did they get to clarifying things? Why do they feel like they have to?

The characters came to clarify things only after a big misunderstanding (Rosalba thought Fernando was the child's father) and a big disappointment (Fernando felt deceived by Rosalba).
Only strong negative emotion opened the door to speaking openly, to telling their own personal stories, including their ‘skeletons in the cupboard', making themselves vulnerable in the eyes of the others. Finally, this step allows the two protagonists to improve the quality of the relationship in terms of openness, sincerity and newly-acquired trust.