I made a bow out of 50/50 for a cake I'm delivering Saturday. It looks good, is mostly dry by now, but it is basically falling apart. The instructions I read said to pinch the various pieces together. Well, everything is breaking apart at the pinch point--so the puffy bits are breaking of from behind the knot and off the tails. 

Can I easily glue these bits together with edible glue or royal icing or candy melt? If so, which would you choose? 

 i mean you could trim your bow with scissors and arrange it on the cake in pieces-- it doesn't have to be all attached -- brush it with some alcohol to clean it or dust it and you're perfect --

another idea:

do you have any product left? i would knead in some cornstarch -- several tablespoons and make a new one -- people like to poopoo this but i once made an old fashioned nurse's cap with the stand up brim that went onto the cake that was already on the display table --  like 15 minutes from serving people already queuing up -- stood up perfect -- with all the sugar in there -- we've never detected a corn starch taste -- just tastes like candy -- works a charm as they say --

best to you 

but that second idea is for going forward anytime you make a piece -- cornstarch is your friend

I use edible glue (tylose and water) for repairs.  I am thinking your culprit is the food coloring, since it is such a dark color.  A lot of gel color tends to weaken the fondant and/or gum paste and make it sticky and not as strong.  I use 100% gum paste for bows and assemble the "tails" and the bow itself on the cake, as -K8memphis recommended.