To play devil's advocate here, we do criminalise lying all the time in cases like fraud, libel, slander etc. It's an offence to lie if you're extracting material gain from someone or if you're ruining their reputation so it's not that big a leap for it to be an offence based on causing emotional trauma. I get the sense that this is not really about one night stands where someone pretends to be rich to help his chances with a girl, but more about cases which could involve long-term deception which prey on someone's vulnerability. Cases more akin to
this guy who would trick women into having sex with him thinking they were paying a sexual bribe to save a relative from non-existent legal trouble. It obviously would be extremely difficult to draw that line when a relatively harmless lie becomes a criminal act though.