People think you are being hypersensitive and they are right.
But also: there is more to it.

You know what it's like when no one remembers you? it's like an official stamp of invisibility. A glowing cape of irrelevance.
No really.
REALLY.

And does that seems ridiculous?
Too internally focused? Too self involved?
Well, then, let me explain.

I am completely 100% aware that more than a fair share of people have poor memories and meet buttloads of people on a daily basis. To expect any one person to remember another is a burden of cognizant recall I would place on no one.
The trick is what happens when they forget. Or don't remember. Or how they don't remember.
It's not what you said it's how you said it.

So there you are. Staring at them. Hi! Hows it going? Whats new? You look nice.

And, you know, the blank stare. There you are, in all your glory and context and you feel like you should ring a bell. Look familiar. Stir a feeling of dejavu. Bring a false smile of recognition.
Something. Here I am. With my boyfriend. In my uniform. In my house. Standing next to my car. You've been in my car. You've slept in my house. You've met my boyfriend. You come to subway every day when I wear this uniform. And still, the blank stare.
And all you can think is: even if they really and truly have no idea in heaven and earth who the fuck you might be, the slightest inclination of respect might make them search their brains for context and clarity and assign you a role. Place you, because you have clearly placed them.

So when someone looks at me and I have met them several times and I know we know people in common or things in common or places in common and I know we have spoken and they have heard me spoken of, and they pretty much dismiss me like a complete and total stranger, all I can think is they are casually letting me know that in the great world of all the people they have bothered to catalogue, I have simply not made the list. I am, even though I am at their dinner table or in their car or buying yet another piece of their art, no more significant to them than a fuzzy face in the crowd. They are looking through me. I am the forest for the trees, and they prefer the beach.

So if I seem to take it personally, I do. I mean, everyone gets allowances, and there are always exceptions, but at some point if I remain a complete and total stranger to someone I have met repetitively, I have to assume they have better things to do than remember my face.