What Should I Do

I HAVE THIS CUTE AND LOVING GUY WHO IS SO GOOD TO ME BUT THE PROBLEM IS THAT HE  JUST CHANGED HIS ATTITUDE TOWARDS ME WITHOUT ANY REASON THEREBY ENDING THE RELATIONSHIP BUT WHAT SUPRISES ME MOST IS THAT HE  CAME BACK ON BENDED KNEES AGAIN TO SAY HE WAS SORRY.HE IS SO LOVING AND CARING THAT I DONT HAVE THE HEART TO HURT HIM OR SEE HIM DOWN SO I ACCEPTED HIM ONLY FOR HIM TO REPEAT HIMSELF AGAIN.WHAT DO YOU THINK IS WRONG WITH HIM.IS IT THAT HE DOESNT KNOW WHAT HE WANTS AND WHAT SHOULD I DO, I FIND IT HARD TO LOVE AGAIN BECAUSE I AM ALWAY COMPARING EVERYBODY WITH HIM.PLS ADVICE ME