The invisible wall

It is like a drawing a horizontal straight line, and at some point it dips downwards, forming a bulb and you come up again, on par with the level of the line drawn previously, almost touching the starting point of the indentation. And you draw straight across horizontally again, as if nothing has ever happened.

So it forms. A line, a bulb with a very narrow opening, and the line going straight on.

It is like a heart, the depth of the heart of someone intensely private. The forced smile, the unreplied message, the way she couldn't hold your gaze for more than 5 secs even though you thought you guys were having a good time talking about that party last week. You want to get close, but do not know how, and on the other hand, you are not that committed as to knock the fourth time. 

How do I know what is inside the bulb? I cannot force my massive hand through that purposefully small hole. 

The bulb whispered, "Pour, pour into me, fill me up, and the water will swirl with my essence and bring my sweetness to you as it overflows". It also said apologetically, "If the opening was bigger, people might think I was flat ground and walk over me. Is it too much to ask?"