Responses
Kodomo x Otona no Houteishiki
http://www.mangago.zone/read-manga/koishite_daddy/
(the plot you mentioned is a bit diff in the basis of that instead of kindergrden teacher, the person is the neighbour to the guy he fell in love with.Neighbour-san has a kid and things happens, they grew up and the kid like the dad's partner but in the end gave up and fell in love with his childhood friend. (that one would be Love Kids)
Oh yeah that’s the one! Thank you so much ^^!
Basically there’s this one kindergarten teacher that fell in love with one of his student’s father. Anyways shit happens,they fall in love but then later when the kid is all grown up it is revealed that he was also in love with the teacher,he later found out that the teacher was dating his father. Anyways more shit happens then the boy falls in love with his childhood friend