Initiating

There are so many levels that are possible to initiating intimacy.  Some people are bold, stating clearly, exactly what they desire.  Some people are extremely subtle, just snuggling up, hugging, or holding hands can be a way to express interest in the possibility.  This can be so subtle that the receiver does not even realize that this is in fact, the person initiating.  When the person who has initiated, in this subtle way, gets less of a response than is desired, this can be seen as a rejection.

The bold partner may be thinking that they are the only one to initiate, even though both people have put in the effort, just in different ways.

It is important to open these lines of communication so the possibility of confusion can be eliminated.

Key phrases can be agreed upon by the couple as a signal that one is interested in the possibility.  These phrases can be about a completely unrelated subject, allowing the couple to have a secret signal that can be used, even in the presence of others. 

This could be a fun way to create anticipation, especially when you are at a public gathering and unable to leave immediately.  (Unless you are brave enough to sneak off to the rest room or other secret location together for a quickie)