Legal Question in Civil Litigation in Canada

Re: Can I sue

Yes you can sue. If the partner knew he /she had herpes and did not disclose that fact to you it is a tort of deceit causing ( potentially ) bodily harm. Query, does this person have any assets? If not a suit would cost you and your recovery would be nugatory ( nothing).

There may be an issue of contributory negligence on your part for failure to enquire, but a person who knows they are at risk and presumably knows they can put you at risk has, in my view, the greater duty. The duty is to ensure against a reasonble risk of harm and the consequential losses .

In addition, this may be a criminal matter you might want to raise with the police.