Found it!!!
It's -
The Prince was my Lover who Threw me Away in my Previous Life~
http://www.mangago.me/read-manga/the_prince_was_my_lover_who_threw_me_away_in_my_previous_life/?e5cX
I believe this is the one you are looking for.
The Prince was my Lover who Threw me Away in my Previous Life~
omg thank you so much
thank u <3
thank youuuu<3
There's this manga or webtoon i cant remember but the MC which is a girl got reincarnated and reincarnated but i believe her first life was she being a commoner and being in love with another commoner(boyfriend) which turns out to be a son of a noble family and was expected to inherit the title and there was like a big misunderstanding that happen that break them apart because of the family of the guy and the like died alone now going in her present life she has magic i think and was training in the palace when she saw her ex was reincarnated as the crown prince i think.
Please help me i know this was a really good story and i don't know why i forgot the title.