I don't want to wear tails

As the groom, you obviously want to look smart on your wedding day, but it’s a long day and you have lots of duties to perform, so you need to feel comfortable as well. If you choose something more casual than tails, it really won’t make too much of a difference in your photographs. I suggest discussing the situation with your fiancée and maybe going shopping together to try on something a little more casual. She’ll be able to see that you can still look smart and dashing, no matter what you wear.