Every story needs at least one villain, or at least antagonist. The nature of life is that one has to fight for one's desire in order to get it. It has been said that story is conflict.
Here's a particularly potent example from my fiction. As you now know, Charlie wants Desiree. The problem, of course being that the two just happen to be sisters. The two have to overcome some fearsome obstacles (society, religion, the law, etc.) and fight some really nasty villains (including their own tyrannical mother) if they want to live together, happily ever after. This is the situation in Bad Company, and it's looking to be a major factor in my 2008 NaNoWriMo novel, Points of Authority, as well.
In Spanner the antagonism is provoked not because Jennifer loves Shira, but because Shira cannot conform (note to self: I'll have to write an entry on this). Conformity is considered a primary virtue in any society that mows down tall poppies and hammers down all nails that stick out. Such is the "Eurosocialism" of the Euro=American Union, the enemies of which bluntly call it "Stalinism". And so Shira finds herself forced to fight battle after battle against authority, society, and religion just to be able to be herself, and she ends up starting a revolution.
This should be a lesson to me. I have a tendency to write scenes with lots of cool witty dialogue but little real conflict, or write feverishly idyllic little love (or other) scenes not counterbalanced by the characters' need to defend their loves (etc.) against social, religious, and political forces determined to destroy them. I have to put some balance into it, and remember that story itself is conflict. In a story, it's the villains (the "rogues' gallery" in superhero-comics terms) that makes the hero; the more effective the villains, the stronger and more interesting the hero. No conflict, no story; no villains or other antagonistic force, no hero.