Wait, you're only 14? Ok...
There are plenty of fish in the sea, every ending is a new beginning waiting around the corner. So don't be quick to get attached to any one of them. Make them earn that attachment.
Learn to recognize red flags and understand their importance.
Bask in the pain (or what you THINK is pain, 14 year old, you haven't seen anything yet, in all honesty) and take it in. Just like lifting, you'll adapt to it with experience and be able to handle it better (please don't confuse me, I'm not saying to go numb and have a lack of emotions). We all have to go through the motions and it's going to happen again sooner or later. Time will help.
In my opinion, don't get into any more serious relationships for a long time, this was way too early. You both don't know what you're doing. Probably why she's doing what she's doing, because she DOESN'T know what she's doing. Start working and paying bills and handling responsibilities before you worry about relationships. Learn how to prioritize and everything will fall into place.
Deadlift. It's good for the mind, body, and soul.