The mistake probably was in the casting (And that is not intended as an insult at all) Whenever that happens at our theater, it is the Director's responsiblity to point out any kissing scenes, etc in the play and then you decide if that is a part you would be comfortable in doing. I applaud your morals.

However, I will say this to anyone else reading my post and once again this is not intended as an insult to anyone, but do keep in mind that this is acting. There are certain parts I would never accept in theater or probably even a few plays I wouldn't ever consider trying out for but you are playing a character, not necessarily a representation of your true self. I tend to be casted in a lot of con artist roles, lol  

Here's two cents from the midwest.

I cast based upon the best auditioner for the role. Period.

The show I am directing now calls for a newlywed couple.  She wants a baby, he's dragging his feet, "we don't have enough money".  Everyone thought our company "ingenue" was a lock for the role.

Not so- I ended up with a mid-30s wife and an over 40s husband.  I simply cast the best people.  At other times I've had under 20s playing mothers of teenagers and once a 14 year old boy as an 80 year old man.  They all worked great!

On the kiss front: I avoid the real deal.  (I agree they can look faker than a fake one.)  I wouldn't expect actors to use a real gun, drink real booze or really hit each other for the sake of "realism".   I do ask auditioners questions about things I think might be a problem, language, will you color/cut hair, etc.  So I usually know in advance.

For the rest: If you approach the director politely it is unlikely that they will mind you switching to Music Man (unless you are set to open this weekend).    It seems like it will probably reduce some stress!   When you have this conversation make sure the Stage manager  (or Artistic Director) is present, and maybe even bring Mom?

Good luck!