It's Always Sunny In Philadelphia: This Theory About The Waitress Will Blow Your Mind
2. Charlie Says "I Love You"
There's a term that people near death experience called "terminal lucidity". Terminal lucidity is when a person's thoughts become clear moments before death and experience an overwhelming sense of clarity about their own emotions. In season 3 episode 4, Charlie experiences this phenomenon and reveals his deepest feelings because he fears he is about to die at the hands of the McPoyles.
In The Gang Gets Held Hostage, the McPoyles have taken control of Paddy's and force The Gang to face off against each other to decide who gets to live. Charlie and Dee team up and, just after he reveals his extremely high-risk escape strategy to Dee, he kisses her and tells her that he loves her but it is never spoken about again.
This happens at 15:02 in the actual episode if you would like to see for yourself.
To further back up the legitimacy of his feelings Mac also uses this near death experience to confesses his love for Dennis. It's no secret that Mac has feelings for Dennis so if his confession of love is taken seriously, then Charlie's should be too.