She likes him he doesn't arranged marriages!

Please recommend me a drama we're there's a couple like Gang Jae and Hyo Jin (what happen to my family). 

He is a doctor, is in love with his ex who is a co worker, The head of the hospital is fond of him so he ask him to marry his daughter who saw him once and liked him, the head doctor said that if he marry his daughter he will help him grow as a doctor, they marry but he still loves the other girl, the wife is rich so she is  not use to doing nothing but tries and after time he grows fond  of her than sees her as a woman and fall in love with her. 

Even if is a secondary couple some thing like that. That  lead doesn't love or likes  the girl but grows fond than in love. It can be from an arranged marriage. 

Maybe something like Le Ratree - The mother of the male lead wants a hero so she is willing to take someone's daughter as payment for his debt. She brings this daughter in her house and want her son to be with her. He don't want this deal and the don't want the girl. But they grow together.

Cubic has a similar story line

not exactly what you asked but...

Marrage not Dating - the start a fake relationship because of different reasons but come to like each other (even if they both try to resist)

TheKing2Heart - he is a prince of the south and she is a military commander of the north. They get engaged but dislike each other at first. A lot of things happens and the grow together

Something like that? I don't know the Drama you mentioned, but if you searched for something like that, I have a few more :)

The three musketeers

It's been a long time since I watched it, although it has a good rating but for some reason I can't remember, I didn't finish it.
The crown prince loves his ex but he got married to another woman (can't remember why) and she loves him so she tries to make him love her to no avail. I know he finally falls in love with her later but I don't know if it has an happy ending since I didn't finish it.

Fated to Love You (there is a Taiwanese and Korean version. I have seen both, I personally would recommend the Korean version.)