i have two words for you: OY. VEY. First of all, mazel tov. Second of all, the fact that couples look alike is because as a general rule (note: general, there are exceptions), people are attracted to features that they find beautiful, so it stands to reason that if your self image is intact, you consider yourself and your features beautiful, and would look for, or be attracted to similar features in a mate. This, of course, is NOT a cardinal rule (i.e. opposites attract) and is DEFINITELY NOT an “inyan”. The fact that people say at vorts “wow, they really look alike”, is because hey, maybe the couple does look alike! (for the above mentioned reason, or any other reason under the sun). People say alot of things at vorts and weddings, would you consider those to reach the level of an ‘inyan’ just because people are yenting about it?
On a more serious note, the sentence “I feel like this is stopping me from being excited over my chosson” is worrisome. Are you actually not excited about being engaged to him, and this look-alike question is just a cover-up for a much bigger issue? Like, are you actually not attracted to him? Or, do you just have this (slightly skewed) idea in your head that couples should look alike, while many, many, many couples that do not look remotely alike (short & tall, fat & thin, fair-skinned & tan etc.) lead perfectly beautiful marriages? I hope I’m not making a mountain out of a molehill, but honestly if you feel the need to convince yourself (even ‘religiously’ by asking if its an ‘inyan’) that you are excited, the questions you should be asking yourself are much deeper than a coffee room about couples looking alike. Best of luck!