We see Sonya as someone who wants a relationship but doesn't want the responsibility. And her Part 3 was mostly about her understanding that she has to make a move or she will regret not being decisive enough.
We won't spoil what's going to happen next, but can confirm the whole "mixed signals" thing is intentional since she's too scared to get into a serious relationship and this whole topic will definitelly be developed further in her Part 4!