You know that one idea for the future that you keep thinking over, that one thing that always seems to run through your mind—that one goal you really just want to reach? Maybe it's getting into a particular school, winning an Oscar, or finally leading the Chicago Cubs to a World Series (that last one really would require a miracle). Whatever that dream may be, it can drive a lot of the choices you make. This is what happens to Jude: as we have said elsewhere but especially in his "Character Analysis," his dreams of going to Christminster and becoming a scholar send him down the path that will lead to everything from love to murder.
By portraying Jude's failure to achieve his Christminster dream and Sue's failure to maintain her goal of a self-defined life, Hardy suggests that poverty and gender are two social categories that can ruin any kind of idealistic plan for the future.
If Jude had let go of the Christminster dream once he had Sue, he might not have dragged his family back there. If he had not dragged his family back there, their lodging and living situation might have been better. If they had had a better living situation, Sue might not have gotten so depressed. If Sue hadn't gotten so depressed, she might not have talked to Little Father Time about how hard it is to support a family. If Sue hadn't talked to Little Father Time about how hard it is to have kids, he might not have killed the babies and himself. And if he hadn't killed the babies and himself, Jude and Sue's relationship might have ended as a happy one. So, there you have it: dreams for the future ruin everything. (Or at least, we think you could make a case that Jude the Obscure is saying that.)