By and large we dismiss such things with moderate contempt for the asshole who did it and fool who fell for it, but 'rape by fraud' which is illegal in a couple states, is conceivably possible even without the victim being dumb, and of course our laws don't permit victimization simply because the victim is a fool.

I think the difference here is that there's a difference between lying about your identity and impersonating someone else. If I introduce myself as John Smith, I'm committing no crime, but if I specifically impersonate someone, that crosses over into identity theft. In a case like that, I think rape is on the table - impersonating someone's boyfriend/girlfriend and having sex with them is rape. We can dismiss the victim as an idiot but that would be wrong, and impersonation could be exceedingly good, and again, the relative naivety of a victim doesn't decrease the crime, beyond a certain reasonable point. Someone's twin could probably pull off an impersonation that would fool even those who knew them very well, especially if they didn't know the twin existed. With the modern trend toward online dating it's quite possible for two people to strike up a strong relationship, meet and have relations, and often one or both are lying in whole or part. But it's also possible for a jerk-friend to be aware of such a budding electronic relationship, hijack it and meet up in their place.

So I would say that in cases where someone is specifically and deliberately impersonating someone else, this is fraud, same as if they impersonate someone to pull money out of the bank, and thus the sex is not consensual and a rape. Big grey area out there, but by and large I'm not going to worry if a few SOBs get hammered by that since you have to be willfully lying to someone for your own benefit for it too happen. This particular case though, he's not impersonating someone, he's misrepresenting himself, same as many do, that makes him a prick and a liar, but not a rapist. Realistically there is a tangible difference between "You're not the person you're pretending to be" and "You're not the specific person you're pretending to be"