Poor poor delusional, living in a pipe dream and a world of false hope Spencer. He has a very serious psychological disorder and definitely has some kind of abandonment issues. If you watched the ep there's no further explanation needed. He needs serious therapy to determine what is causing all this.
Oh, and one more thing...you just read my signature.
He is either delusional, stupid, or has a affliction of some sorts.
I can see him as a full blown stalker in the future.
I felt a tad bit sorry for him, poor bastard was the punchline the entire time and he didn't seem to get it. Max could barely contain his amusement at Spencer's stupidity.
It was an online variant of Fregoli Delusion: https://en.m.wikipedia.org/wiki/Fregoli_delusion (online as opposed to meeting someone in person and believing they're in disguise).
A delusion is different from a deceit. A lot of catfished folks suffer from having been deceived. The persistent, obsessive nature of Spencer's conviction indicates it's a delusion. As for his brother, psychosis tends to run in families. It may be mocking the afflicted or mental-illness-shaming to blame the brother (for not trying to disabuse Spencer of his poignant belief).