Season 4, Episode 5 opened with Stella stealing everyones' drinks and she needed them. She just had to deal with her one-upper sister who's about to get married and stole Stella's dream wedding. However, when things go wrong with her sister's relationship days before the wedding, Ted (inadvertantly) and Stella agree to move their wedding to that weekend so she doesn't lose any deposit money. There's barely any time for Robin to come back from Japan or for Barney to plan a proper Bachelor party!
Barney, for once, is actually pro-marriage as it's part of his plan to sleep with Robin again. According to the formula he came up with in Numb3rs fashion, he needs to get Robin drunk at Ted's wedding and he's in. However, when Stella's horny vegan, out for revenge sister, tells him she needs meet, he may not be able to hold out for Robin to come back. Barney's plan is further foiled when he finds out the resort they're staying in has a astrict no alchol policy.
When Ted tells Stella that he invited Robin, she informs him she has a strict no exes at the wedding policy. Doesn't seem too crazy to us. Lily tells Ted to break it to Stella that Robin is still coming after he avoids a crisis. When Ted finds out Stella's daughter is unable to go because her ex, Tony, is holding the daughter hostage, he sees his ultimate chance. He heads out to New Jersey and gets both her daughter and Tony to come to the wedding. it turns out the reason Stella didn't want exes at the wedding is because she still has feelings for Tony. Stella leaves Ted for Tony. Ouch. Can't say we'll be sad to see Stella go.
If things couldn't get any worse, Robin shows up to to Barney's room with a bottle of scotch and looking to score. Too bad he couldn't contian himself and has the girl at the front desk in his bed. Maybe next time Barney. Good news is Robin quit her job in Japan and moved back to New York so you'll have plenty more chances.