Hello SSKF,
You can try these (if you haven't already watched):
1. The Romance of Hua Rong : The Male Lead is protective and possessive. He falls for her in the 1st episode itself. The plot is mainly focused on the romance between the two. Lot of fast relationship moments. The ML character in this is still one of my fav.
2. The Romance of Tiger and Rose : This is super romantic. The ML falls for her pretty soon. He is super protective. Lot of cute (& jealous) relationship moments. The focus is on the romance while the main plot provides a background beautifully.
3. Love Better Than Immortality : The ML is already super obsessed with the female lead (and no other girls). He is protective of her. The ML is kind of a bad guy. Lot of intense flirty relationship moments. The plot does have other things but mainly revolves around the pair. Pretty sure to make you swoon..
4. Unique Lady : The ML falls for her early but does not reveal it (since he portrays a cold side to the outside world). He becomes super possessive. There are many romantic relationship moments.
The FL is same in 2 & 3 (my fav) whose acting is awesome which makes it worthwhile to watch. Hope you can enjoy these!
Please do recommend me any dramas similar to these mentioned (& cruel romance) if you find later.