Thank you for your question. In the book Islamic Laws according to the rulings of Ayatullah Sistani and translated by Shaykh Mohammed Ali Ismail he says:
"If someone keeps a recommended fast, it is not obligatory on him to complete it. In fact, if a fellow believer invites him to eat, it is recommended for him to accept the invitation and to break his fast during the day, even if it is after zuhr."
May you always be successful