The problem here is that we are only partially talking about language. We are also talking about complex interactions of emotions and social convention. By starting with ”stalk,” you have created a framework that is necessarily negative. “Stalk” has a meaning that connotes predator and prey. From the standpoint of the prey, there is no positive aspect to that relationship.
Someone being interested romantically in someone else is not considered as being negative by most people although it may be annoying in some cases. No one believes that it is a crime for A to have a romantic interest in B even if B does not reciprocate. What are crimes are certain behaviors that may be motivated by a romantic interest.
You seem to pass the time with me a lot. If you like me, why don’t you ask me out?
That sentence does at least imply some level of annoyance, but not annoyance at being liked.
Here is where we get into the social and emotional. If male A is spending a lot of time with female B and B has no romantic interest in A, it makes neither social nor emotional sense for her to ask why A has not asked her out. That question is very likely to elicit being asked out. That question is a clue that B is at least curious about A.
It is hard to answer your question because you have not specified the circumstances that induce B to ask why A has not asked her out. Finding the right word requires context.