when is it time to call it quits

all my life i've been a quitter. i gave up on things that always had potential. even things like music and art that i had a passion for didn't seem to hold my attention for to long. i've always given the piece of advice, if you're not happy, time shouldn't be the factor holding you back regardless. in my last relationship, everything was completely wrong. i gave it my all, i gave him my heart, i gave him everything that was ever asked and more. after hitting that one year mark, the last few months, my ability to feel emotions had numbed. and no matter how many nights i cried myself to sleep, and all the time i spent with a smile on my face convincing not only others but attempting to convince myself that i was happy and in love. the day he broke up with me, scarred me. i can't remember what day it was. some time in june i believe. but the beginning of that summer was one big blur of tears and tissues. it was hard looking back on the past year and few months. i had given all i could to a lost cause. i didn't know when to quit. 2 years later, i still don't know when to quit. i love him so much, but it's so hard. i keep thinking that with time things will get easier...for him and for myself. it's hard to talk about things without thinking about it. and it's selfish of me to ask that he not talk about it regardless of whether he regularly does or doesn't. instead of considering how he feels, he worries more about me. i love him so much and i know every relationship has hardships. this just seems to last all the time. i guess the bottom line is, i'm mad because i have to suffer for his mistakes and his selfishness. i'm upset at the sacrifices i make. i'm angry at his stupidity. but i love him. i just don't know what to do with myself.