The story for the manga goes like this: A girl and boy are childhood friends, she wants to become an actress/model (beacuse she likes some dude who is an actor) so she moves to the city, he (being in love) follows her to the city and end up being recruted to be an actor/model in some kind of group where, obviously, the other guy is the star. Lot of things happen but, at the end, the mc falls in love with the rival girl of the first one.

English is not my forte so forgive me.

My first thought is Skip Beat however some details are different in it:

In Skip Beat she follows him to Tokyo because he wants to be a popstar. Whilst there, the boy develops a one sided rivalry with an actor who won the polls for 'most beautiful man in Japan' (or something like that) which the boy had been nominated for. Then the boy leaves the girl and in revenge she becomes an actress. At this point she ends up appearing in the same drama as the rival actor. Then yes, lots of things happen and the popstar ends up falling for the girl, but the girl is the mc and the rival actor is really the main love interest.

Full Dozer?

DONDAKEE!!

Yes, it was Full Dozer, thank you