I arranged a wedding with Ysolda in Riften and fast traveled back to Whiterun to get nice clothes to wear during the ceremony. When I make it back to Riften it says I missed the wedding. Just as i approach the temple everyone is walking out and Tsolda won't talk to me. When I try talking to her all she says is "how could you" in a crying voice. How can I amke it up to her? I f'ed up.

You should be able to talk to either her or the priest, apologise for screwing up and arrange a new wedding for the next day. You might have to wait 24 hours before being able to talk to anyone/