saw someone posting this on tumblr see if anyone know it here [HELP] Do you know the titl...

saw someone posting this on tumblr see if anyone know it here
[HELP] Do you know the title?
Looking for yaoi manga that a boy loved his brother and hated his male lover in his childhood (saw them had sex) and after years he was going out with a man that looks like his brother’s lover. They working lab like place and after it was cleared that actually his brother was himself so it is about time travel. It was not a long story. And he tried to keep his hair long to in order to look like his brother. But one day he and his lover save a boy from past time. Then uke understood everything and decided to make new begining and start really love his lover. Even in sex scene, when seme said child was watching, he said let him. And I remember seme was big, black haired, dog like man. The child was rememering his brother in some field and at least, child was sent his time and those two scolded for interfering with the time.