What's movie a two neighbors hate each other but fall in love online?

What's movie in which two neighbors hate each other but fall in love online p.s he names himself online hopless1 and she names herself hopless2? by the way it is similar to You have got mail but it is different. During the movie before they fall in love they used to tease each other, and cause neighboring troubles to each other. in the end of the movie he thinks that she was gonna marry and he hurries to stop that marriage but finds out it was her friend's wedding. Can any one help me?