Are you thinking about getting married?
Are you feeling like you are the only one that cares about the relationship?  Are you two on the same page?  This subject seems to have anxiety around it for you.  Perhaps you feel like if you were to get married it would be all your idea and your boyfriend would only be going along with it because you want it.
The preacher not showing up shows that you feel as though you don't have everyones blessings as far as your relationship goes.  Perhaps you need to let go of what everyone else thinks and just focus on you at this time.  Marriage doesn't always have to proceed dating.  And also you may be having strong feelings of abandonment from this relationship and others around you.  You feel as though you need more support from your boyfriend and relatives concerning what is really important to you. This dream resounds feelings of anxiousness and abandonment. Hope this helped clarify things a little.