Khosi has been denying whatever feelings she has for Thabang, she has even gone as far as absolving herself and apportioning the blame for the sexual chemistry between them to him. This might be unfair because as much as viewers can see she flirts with him too.
Their discussions have revealed they are trying to set boundaries in their friendship. It takes two to tango and from her actions Khosi has proven she is not ready to dance to the tune of distance with him. Instead of trying to ease whatever crush he has on her, she is strengthening his feelings.
Just today, the 21st of February, she moved to his bed topless. She went to meet him for whatever reason with the upper part of her body bare. This might not be unusual in her culture but one would expect more caution from her side she knows the situation with him and Yemi.

Her actions can be read as an encouragement to him and the moves he might be intending to make. There is no reason a female would approach a male with her boobs all out except if she intends to seduce.