Dragon Age: Origins romance question?

If Alistair made me choose between him and Zevran, and I picked Alistair, is there any way Zevran and I can be "more than friends" again? I'm regretting that I didn't choose Zevran. It's not a big deal, I know, but it just makes the game that much less enjoyable for me. I tried ending it with Alistair and then talking to Zevran, but when he asks about me and Alistair, there is no option for me to tell Zevran that I changed my mind.