Definitely a webtoon, i remember their names being Korean and it was in colour too. The girl’s hair was ginger, the ml’s hair was black and the guy they were spying on was blonde. I think the romance trope was leaning towards a love triangle- ( the cover had the three of them in it and both were looking at the girl ) the art style was very nice too
I was looking and I think you didn't even read it on this site cause it's only on Webtoons
It's "I Spy a Married Life"
https://m.webtoons.com/en/romance/i-spy-a-married-life/list?title_no=5546
Im looking for a webtoon about two secret agents, male and female, and they are trying to get dirt on this guy and to do that they pretend to be a married couple. The girl is very delulu and the guy wants nothing to do with her and I think it’s a fairly new webtoon. I was reading it a few days ago but I can’t find it anymore for some reason, I don’t remember the name of it or any of the character’s names :’)))