"It's so cute how every second we spend together grates on me.""That outfit makes you look like a grunge elf.""Your twitter is not as good as Jake Johnson's twitter.""The way you sneeze makes me vomit in my mouth a little.""I miss sleeping with my ex... :(""I miss being single... I miss ME."
Any and all of these things will destroy your relationship. Never, ever say them. Ever.
You're welcome, OK?