just because she's glad he's alive doesn't mean they're a couple now.
though, considering the previous family arrangement, i wouldn't be surprise if they became engage.
I was about to object that last time, it was for political reason and the mom fall for it; Serena would know better not to take their family into a tough spot again...
But, then I realized, the tension was because Hera's faction was stirring up shit, wasn't she? So... there's actually no reason outside reason stopping her from doing so anymore...?
PS - I actually took a peek of the ID translation since the release of the chapter 18.1/.2 (they released faster than EN) and already know Serena will directly confronts Hera, but damn, I totally missed the snap sound effect right there, thought Hera just sat there in shock.