My thing with this sex = achievement unlocked? stuff here is that it's a matter of what you perceive to be important to you, which is shaped by our present western culture. The "achievement" part is just construct. Let me explain. first of all not everyone in the world thinks in uniformity about a sexual encounter/first time sexual encounter. In the US and the west, it is generally viewed that boys and girls should have sex and it is "right". If they don't, parents, friends, relatives or colleagues might think there's something wrong, etc. The media and our culture promotes this by tying societal acceptance with having sex. So when you do have sexy time for the first time, you feel "cool" and accepted, or part of the herd. This is the result of the sexual revolution of the 60's, where having sex before marriage was the defining characteristic of a youth disillusioned by the establishment and the painstaking norms of the old where the world is ruled by only Men (capital M). No kids allowed. Only Men do cool things. Men run businesses. Men are great. Men rule the world. Then Rock n Roll came along and really a paradigm shift happened. It gave the youth a voice.
I'm not saying that sex outside marriage did not happen at all before 1950 in the US. I'm talking about a general perception of it changing completely in the US. But in many parts of the world, the world is still ruled by Men (figuratively). In these places, sex outside marriage is seen as a shameful act that will bring dishonor and drag the family name in the mud. You are an outcast if you have pre-marital sex, instead of being the "cool" guy in the west. People will label you all sorts of names. This is their perception according to their cultural influences. The sexual revolution or the demystification of Man's Dominance hasn't happened in these countries. But slowly we see their societies also becoming greatly influenced by the west due to the pervasiveness of our music, movies, TV, books and now the internet. I'm not passing judgment on western cultures vs eastern cultures. It's just how our societies took shape.
It's important to know why we view sex like we do, especially if it's the first time. It's all about how society perceives it. So if you're thinking "boohoos I'm a lonely nerd and I will die", don't. The pressures are making you feel that way. Think about it. If you were born in a different culture or sometime before 1940, you'd be the paragon of greatness.