It usually signals that they are the weaker in the relationship are appeasing in private then when they think they might have allies challenge you. It is very hurtful behaviour. It is beyond the pale. Make it a rule with him that you don't betray each other in public. as others have said it is manipulative cruel and passive-aggressive and cowardly. grrrrr
Good luck with clearing this up and get back to us for further support.
: What has been your most wasted purchased made in preparation for a holiday?
Why on earth would anyone plant.....

Depressing to think that there's more than one of them around.