I dated the same guy for 5.5 years and in the end, I just felt like it wasn't meant to be anymore. We split and he immediately got a new girlfriend, so I just started doing my own thing. I met another guy and fell so hard for him, but he had been burned and didn't want a girlfriend anytime soon. He definitely wasn't lying because I'm pretty sure he is still single now and this all happened back in 2008. After that didn't work out, I just decided to focus on myself and school and enjoy life.
It was my first year as a declared accounting major and I started taking my upper level classes. In one class, there was a group project where the teacher assigned the members. The group worked pretty well together and everyone was really nice. One day, our second project together was due when my computer decided to take a shit and I lost my part. I called one of my group members frantically because I thought he was the only one who would help. He came to pick me up so we could work on it and I thought it was really nice that he stepped up like that (obviously there is self interest because his grade was on the line, too, though

). As we were working, we got to talking and had a lot in common. We eventually started hanging out more and more and now we've been dating over a year.
I'm a firm believer in this quote, "good things fall apart so better things can fall together." It may not happen right away, but everything happens for a reason. I didn't date anyone for a year and a half after my relationship ended and definitely had my heart broken in between, but it only has made me a better person. The time away allowed me to know what I wanted for myself and at least gave me somewhat of an idea of what I wanted to do with my life. I'm just really happy right now and I owe a lot of it to just getting my own shit straight and focusing on myself.
I know it's cliche, but there are plenty of fish in the sea. The great thing, too, is that you are so young and have so much of your life in front of you. After a break up, sometimes you just feel any relationship would be better than none. It's definitely not true. Focus on making yourself a better person (in your own eyes, not someone else's) and put yourself first. Do things that make you happy, pick a goal to work on, volunteer, or a combination or whatever. I feel that if you can show people that you can take care of yourself, then it shows you can definitely take care of them. That's an admirable quality.
I know it sounds annoying to have people sitting here telling you, "it's just one girl" or "you're young, don't worry" or whatever, but we have felt just as you have and had people tell us the same thing. It is true, as much as we don't want to admit that we didn't think so at the time.

Not to mention, Valentine's Day just seems to shove everything in your face. Honestly, on the Valentine's Day I was single, I was out job hunting because I found out I was laid off just a couple days before. I went to Red Lobster to apply not really thinking about what day it was, only to see it slammed packed with a 3 hour wait for what seemed to be a countless number of couples waiting to eat. It was a little depressing, not going to lie, but it is what it is and I didn't let it bring me down that day.
Okay, I've said a lot. PM me if you ever need to rant or anything. I love listening.