I feel like the author tried to imply they did because the male lead texted the female lead "hey I'm a wolf" before he went to bath and the female read the text. And by the end of the chapter when they were cuddling female lead said "hey I'm a sheep" to the male lead, and then it shows male lead was quite shock and the chapter ended with them under the blanket covers. I'm assuming they had sex. I might be wrong.
Everyone is freaking out. Eventhough this is a very fluffy and soft manga but yes the male lead slept with a lot of girls before, had have threesomes and shared girls with his other friends too. However he kept it a secret from female lead because he didn't want her to know he was "dirty". I feel like in the future chapters, his past will be revealed to female lead eventually especially with the appearance of that new girl.
However, it has been shown several times how this is the first time for him falling in love with someone and getting jealous. E.g; he refused to share female lead with his friends unlike before, he doesn't care if his friends stole his "women" before but he gets angry when it comes to female lead, he for the first time wants to stop smoking all for the sake of female lead + many other scenes.
and yes, female lead and male have slept together/had sex in volume Two.
Thank you for the uploader for picking this up.
Can't wait for what the future chapters hold! The dramas and conflicts in this manga are usually resolved fast so looking forward to see how female lead confront with male lead's past.