Dealing with unrequited love

Once upon a time there lived a guy and a girl. They met by chance over internet. Something started as an online friendship for a few weeks extended to eight months.

Over a period of time the guy started developing some sort of feelings for this girl. And when she proposed to discontinue the contact, they guy was shattered and they somehow continued the friendship. The girl valued his company and opened up about all her things even a few of her friends doesn’t know about.

And then a crisis happened. The girl decided to reach her ex for support. Guy told her he could do that. But practically its not possible. Still he supported her to reach the ex and she moved in with him. Simce she was soo done with this wd guy, this time it was simply platonic and he just wanted to help. But the guy became possessive and insecure about she staying with her ex and sharing the same bedroom even though she stress again all things are platonic here.

How should the guy deal this?