Someone fancies you, Receiver. Could it happen? is a simple question, but one with significant implications. The Bearer implies that they're interested in a relationship – whether long-term or otherwise – and should the Receiver reply in the affirmative, they will make their feelings known more directly. Such an overture marks an excellent opportunity to let someone down gently, as a Receiver is free to say that they are, for example, in a relationship and unable to proceed as the Bearer would like – whether truthfully or otherwise.
To respond positively, a Yes has the virtue of simplicity, while I like you reassures the Bearer their sentiments are enthusiastically reciprocated and degrees of enthusiasm can be expressed through We want different things or Drink?. Patience assures the Bearer that the Receiver will be at their service as soon as may be, and those whose situations call for a more sophisticated response than simply ‘yes’ or ‘no’ have It's complicated at their disposal. In stating unavailability, a regretful Bearer may respond with Alas or If only, whereas Mind your own business requests the Bearer keep their curiosity to themselves in no uncertain terms, and You're not my type or even a simple No make the unlikehood of any further engagement clear. Should the arrival of such a message have had negative consequences for the Receiver, they can make this clear to the Bearer with a direct You shouldn't have done that.