The Royal Prince's First Love
Rebirth Two Lives - I Still Love You
Uke have second chance at life because of seme (unknown to the both) they both return to the past and uke is finding out that the seme has been helping all this time and not as cold as he thought he was before in the past life.
The Concubine is a man
Uke was sent as replacement concubine of neighboring kingdom because of prophecy that she would live a good life (prosperous) if they send the person from the prophecy to the kingdom as her replacement (the uke). The king (seme) notices he is not the real concubine but started to fall in love (feel special) toward him and possibly be reencounter moment from someone in the past. Uke is able to calm the headaches of seme which is why seme starting to fall in love
Fall In Mistaken Love