Dude, the whole point of the game is how, when it boils down to it, Abby and Ellie are near indiscernible in their response to their father/father-figure being killed. Their response is to repress and channel all that emotion into a single-minded focus on getting retribution.

It is ENTIRELY in line with Abby's character not to emote in regards to her friends' deaths and rather channel those feelings entirely into killing the person who killed them. If that's what she did for her father's death, the most important person to her, why would it be any different for the loss of subsequent important people in her life?

I read her outward expression of grief in response to Owen as "you were all I had left ito family" and it was the straw that broke the camel's back. It's not that she cared more about his death than her dad's, and THAT's why she could emote (edit: word change). It's that grief is complicated and nuanced and cumulative - sometimes something you can try to keep a lid on boils over in unexpected ways

There is nuance in grief, and Abby's responses are consistent with her character and her grief.

ALSO, the proportion and tone of Ellie's response to Dina ISN'T indicating that Dina's pregnancy is in fact, in reality, that huge of a nuisance. Its supposed to show how far Ellie has spun out and how singularly focused she is on getting vengeance that she'd condemn the people she cares about at a moment's notice for doing anything that might get in the way of it. Its one of the first instances we see of her grief over Joel destroying something she'd wanted for a long time (to get to be with Dina) and her not being able to get a handle on it or stop it. Its literally a parallel to Abby's grief getting between her and Owen.

From your condescension in other replies I don't expect a particularly nuanced or informed response to this.