5 things to do before our 5th anniversary

Isabelle Esguerra and her boyfriend Andrei Robles listed down 5 things to do before their 5th anniversary. Unfortunately, they haven't done a single thing on their list because Andrei committed suicide leaving Isabelle a letter stating that he decided to end his life because he is gay and cannot find the acceptance of the society for the LGBT community. During Andrei's funeral, Isabelle met Angelo Lacson. Isabelle somehow liked Angelo because he is inviting her to do the things listed on the "5 things to do before our 5th anniversary" notebook without him knowing it. It turned out that Angelo knew about the notebook all along and decided to do it with Isabelle not only because Andrei passed away, but also because he would do anything to make her happy. What is the role of Angelo in their lives and why does he know about the notebook?