Oops, it doesn't look like 'get cheated on day' is a national day..

Other days

lash

Lash Day
ponytail

Ponytail Day
artists

Artists Day
brow

Brow Day
eat what you want

Eat What You Want Day
healing

Healing Day
cuddle up

Cuddle Up Day
cursing

Cursing Day
prosecco

Prosecco Day
promposal

Promposal Day