If I'm struggling with writer's block, I'll walk away from that scene and work on a different scene in the book. Sometimes my brain doesn't want to be dress shopping for a wedding dress. Sometimes, my brain's just jonsing for a bar fight. So, I write the scene for the bar fight and save the dress shopping scene for another day. For this reason, my books aren't always written in chronological order. Often, the last chapter is written, long before the middle of the book.