You have to be emotionally available, make them feel heard, help out around the house, acknowledge them, buy them flowers, take them on dates, don't try to control them, treat them as an equal and treat them the same way you treated them when you first started talking to them. Oh and you have to be consistent
Don't forget to walk tall and carry a big stick.
Meanwhile mental health has trashed your confidence and they're just a shroud of some onceman.