A defence officer cheated my friend…

I just need advice on whether we have a strong legal case and if it can be taken to court, considering he’s under military protection and what can be done in such situation.
My friend and he were in a situationship in 2019. He cheated on her with another woman, dated that woman, got engaged to her, and allegedly cheated on her as well. During that engagement, he accepted a gold chain, cash, and a phone before.

Years later, he contacted my friend again and spent months convincing her that he had changed. They got engaged, during which he accepted a gold chain, cash, an additional ₹1 lakh because he claimed to have no money, and around ₹50,000 worth of clothes for his family. My friend also pays half the EMI for a car loan he had taken just 10 days before the engagement. She spent thousands decorating their future home in the cantonment and even sent him a scooter for local work.

When she discovered he was cheating on her continuously post engagement , she informed his parents . He then broke off the engagement, saying, “I don’t feel anything for you. You defamed me in front of my parents.”

I want genuine opinions to how to go about this ?