Relationship Catfishing
Criminal Law
There is a variety of criminal offences that are captured by conduct that may accompany catfishing.
Sexual Offences are relevant to those who have experienced sexual actions/activities that they did not consent to, this includes conditions for consent. If you imposed conditions related to the 'nature or purpose' of the sexual act. This would also be the case of the perpetrator lied as to their identity, this follows a much longer precedent. We won't go into depth on the various offences that one might suffer from but it is worth looking at the Act as this rule for deception and vitiation of consent applies to all of the sexual offences.
The relevant law for this if you are interested can be found in the Sexual Offences Act 2003 and R v Clarence
There is an offence under section 76 of the Serious Crimes Act 2015 that is relevant for catfishing. It has also been invoked in the well known catfishing case of Sweet Bobby. This offence seeks to punish coercive and controlling behaviour. This is unfortunately not applicable where the perpetrator has responsibilities over the victim who are children. This behaviour that is controlling or coercive must cause the victim to fear that violence will be used against them on two occassions or serious alarm/distress which has susbstantial adverse effects for the victims daily life. It is also the case that the victim must have a personal connection to the victim, this can take the form of relatives, civil partners, spouses, fiancees, or another person who has a parental relationship with the same child. These are all of the requirements but there is a defense to be wary of. It must be the case that the perpetrator thought that it was in the best interest of the victim and that it was reasonable, and this defence is not available if fear of violence was involved in the commission of the offence.
There are many cases that describe coercive and controlling behavior but there are few that are catfishing based, If you are more interested in information we suggest the cases of R v Willey, Regina v Chilvers (Peter), and F v M.
Civil Law
In the case you want to purse civil action there is a tort which may be of relevance with emotional harm. The Tort of Intentional Infliction of Emotional Distress. Unlike what it is called there is no need for it to be intentional, the lowest mental requirement is negligence. The qualifications that are a bit more important is that the distress is caused by extreme or outrageous conduct and the harm it causes must be severe.
Unfortunately there is not much in the way of guidance for the definitions of severe and extreme or outrageous. If you are interested in more information the main cases for the common law tort are O v A [2015] UKSC 32 and Wainwright v Home Office.