low-key low-profile
since he did not care about you , you should not take her so serious.
低调 a low-key guy
Now that he doesn't care about you, you needn't have to take notice of him.
low man
don't care about her as how she did to you
low-key person低调的人
Since he doesn't care about you that you should ignore him
low-pitched person
Since he doesn't care you,then you don't need to take him serious
低调的人: Low-key person