Hey, so I'm looking for some drama series that have two or more romance plots/couples going on at once- preferably separately and not entangled in triangles or squares. Jdramas like that I enjoyed were Watashi ga Renaii Dekinai Ryuu, Tokyo Friends, Brother Beat and Propose Kyoudai, but I'm open to any language. Thanks a lot!! 

- A Clear Midsummer Night (C-drama, 50 eps)
- A Gentleman's Dignity (K-drama, 20 eps)

In general, family dramas tend to have multiple love lines, but if you're only into short format j-dramas then most K and C-dramas in this genre may not be for you because they're usually upwards of 30 or more episodes.

I think you can try watching the Lover - Kdrama. The story zooms in on 4 couples who lives in an apartment complex,
Was going to suggest the Lover too. Although I am yet to watch it.

Most dramas that I have seen have a secondary couple who aren't the mains of the show alongside the main couple. 
Thanks for the suggestions! I'm watching A Gentleman's Dignity right now and loving it, and The Lover seems really good, I'll watch it soon. I know there are often secondary leads in all dramas and I tend to invest myself in them, but they're often ignored at the end, getting an off-screen confession at most. :( I hate it when I'm disappointed that way.