This is the second time I've had this dream. Not exactly the same, completely different locations and men, but the same dream. So I'm planning a wedding with my fiancé.
In my dream this time we had been dating a long time but he didn't want to get married so I got engaged to his cousin who I knew in high school. And now we are planning this wedding and we're pretty far into the planning. We've spent a lot of money and booked everything but I don't want to marry him. I want to marry my fiancé. So I end up leaving the cousin and going back to my fiancé. And that's it.
In the other dream I was planning a wedding to my ex and it was as close as the weekend before the big day. And I had this awful feeling of dread. That I didn't want to marry him. I want to marry the man who is now my fiancé. So I leave my ex and marry my fiancé in his place.
What does this mean?

Hi.
In your dream, each of these guys represent different aspects if your action or behavior. Marriage symbolizes a commitment between your thoughts and actions. Your dreams are showing how you are struggling with choosing what it is you want to do. In other words, you have a desire to do one thing and end up doing another. Look over your life and see what kind of activities/actions do you find yourself jumping back and forth, trying to get the right one.
Hope this helps in some way!

These are fairly common wedding anxiety dreams. As with all dreams, they are symbolic expressions of your feelings, thoughts and awarenesses (including intuition) about your waking life at the time you had it. Here are some links to definitions of the symbols in your dream on this website:

ex-lover: dreamdoctor.com/component/dreams/?contro...&task=details&id=726 (there's a good video about this on the homepage as well)

wedding: dreamdoctor.com/component/dreams/?contro...task=details&id=2004

Try to recall what was going on in your waking life just prior to having your dream. For instance, in the first dream, you may have sensed some "resistance" to some aspect of wedding planning that reflected itself in his not wanting to marry you in the dream. In the dream, you opted for the next best relation (his cousin), but that did not diminish your desire to marry your fiance, as you eventually go back to him. In waking life, you know that your fiance's "resistance" is temporary and in waking life (and in your dream), you know that it's all going to work out.

Your second dream is a classic ex-lover dream. Why he appears in your dream may reflect some feelings of longing for the best of what you had together (qualities that may not exist in your fiance), but it's clear from the dream that you know that partnership would not have worked ("feeling of dread") and you rightly replace him in the dream with your fiance... because you know, even subconsciously, that he is the right choice for you.

Hope that helps. Congratulations on your engagement!