I've seen some side character storylines in dramas and also some where there might be non-romantic relationships between debt collector and female lead who has to pay it back for her family or spouse (like in Liar Game kdrama there was a strong non-romantic friendship between collector and female lead). 
Did not like (Can love become Money)
There was a little in The Gentlemen of Wolgyesu Tailor Shop, where the debt collector was smitten with female lead even though he has thug like background, he still paid off the debt for her and wants to marry her.
I wouldn't mind something like that if anyone has recommendations. thanks! 
-HapiMari: Happy Marriage stars a woman who has a debt and a rich guy offers to pay for it. (The drama is not great overall though. I'm gonna finish it but I can't rate it above 6.5.)
-Marriage Contract (which I enjoyed) stars a widow who struggles with a huge debt and considers marriage to a rich guy to cover her expenses. (Enjoyed this drama.)
Off the top of my head:

- When A Man Loves (South Korean movie)
- Zeni no Sensou (Japanese drama--> both of them really care about each other, but I think what they feel for each other is affection, not romantic love)
- Money's Warfare (South Korean drama--> I haven't watched this personally, so I can't really vouch about it)

thanks for all the suggestions I will check those out. ^_^