Y'know, it's sad that people even feel the "need" to stalk in an online setting. Some people really need to get a life...
But I have, actually, experienced this myself-- not me stalking someone, but someone stalking me. It was years ago back when The Sims Online was still in service, maybe a year or two after it launched... There was someone with an avatar that looked like an old lady, and she kept following me to every lot I went to. I'd go to a lot, there she was, I'd leave and go to another, she'd pop up again... The person didn't actually do anything or say anything to me, she (or he) would just appear on the lot... maybe would interact with some objects, but keep their distance from my character. It was... strange.
I can't remember what I did to get rid of them. I imagine that I probably put them on my ignore list, which (if I remember correctly) made it so they could not see where my character was.
After all those years I still remember that... >>;;