Everyone has one, if not many, pseudo-friends. Odds are that not only do you have them, you are one yourself. A pseudo-friend is an acquaintance that you have around campus that you used to have a close relationship with, but aren't even on speaking terms anymore. You have fallen out of friendship with your pseudo-friend not because of a huge fight or because one of you moved across the country, but because the situations (bio lab) and terms (loneliness) that you became friends around no longer exist. Every college campus is teaming with pseudo-friends, and you can't take a walk from your dorm to your history lecture without running into a few of them.
Most often, pseudo-friends are born out of freshman year and the dorms. Think about it: it's the first week of school, you don't know anybody, you don't have any friends, the kid who lives down the hall has Mario Kart; you're best buddies! College is great! This is exactly how I thought it would be! Right? Wrong. Time passes and you slowly realize that your "friend" is actually pretty weird, and only after you meet people who share the same interests as you do you stop hanging out. And he does the same thing. There is a mutual understanding among both parties that both of you have moved on. But that doesn't mean that you still don't see each other every Monday, Wednesday, and Friday walking into the cafeteria for lunch. And of course you smile and say "hi" right? Nope. You don't even acknowledge that the other person exists. Welcome to pseudo-friendship.
A lot of pseudo-friends are also born out of classes, especially group projects. For 15 weeks you spend countless hours in the same library study room putting together a group project, but once the professor hands out the final grade: welcome to awkward social interactions. You still see the same person, maybe it's in class for the next 4 years or when they live in the house directly next to yours, but you fail to muster more than an awkward wave. Not only do pseudo-friends make for unbearably awkward situations in private, they make for even worse situations when pseudo-friends are combined with your real friends. They're like oil and water; they simply don't mix. If you are ever at a party with your real friends and your pseudo-friend is there, and one of you is drunk enough to think, "Hey it's Josh! We had some good times in the dorms watching Reno 911 together; I should go talk to him," save yourself the embarrassments and walk away. If you do try to go talk to your pseudo-friend, you will have to introduce him or her to your real friends, and you'll have to explain how you worked on a biology project with them 3 years ago, and that's about it. You both haven't thought of each other until you just locked eyes across the bar. End of story.
Pseudo-friends are like the animals at the zoo: best kept at a distance. You treat them with care and respect, and most importantly, distance, and everybody's going to go home happy. If you don't, and violate the terms of the pseudo-friendship by attempting to initiate contact with them, then everybody suffers, and most likely one party is going to have a horrific story to tell to their real friends at a later date.