Why doesn't my husband care anymore?

I've been with my husband for 9 years and recently just got separated, i still love him but our relationship just got to the point where he's crossed the line so many times in different ways possible and after all this im still hopeful, i still call him and i still care but its not like that for him at all, he doesnt try to make up for his mistakes and takes things and me for granted. what i really want to know is why after you give up so much time and effort for someone they act like you're not worth it? i mean, im a good looking 24 yr old woman and other men would wish i was with them but the person that i want for to care that way doesnt.Men out there please answer this ...