How do I fix my relationship when it's already close to the end?

Maybe get your life together before you start worrying about him. If you can straighten out your life, you won't have so many outside stress factors that put stress on your relationship, and therefore you have a less stressed out relationship and you can also invest more time into repairing it. I understand that you're a teenager, you have a right to be stupid no offense, but honestly get away from the pot and alcohol and start to plan things out. You can't just have a fight with him and tell him things need to change, you have to take initiative to change things instead of just whining about how they need to. Maybe even reevaluate your view on love. Is this a redneck kind of lust or is it really something that can work? If not, you just have to deal with it. People come and go, and the ones who stay and fix things are the ones who are worth keeping around.