If you go check the original author's pixiv you can clearly see he's a big fan of Gundam Witch from Mercury, not to mention, ah, the original twitter one off comics went like ten times harder on the gag that Anna is clearly very, VERY gay for Grace. There's moments the daughter even says "Uh... Dad...? Just what kind of flags are you...?" clearly spotting Anna crushing harder on Grace.
Even if Anna doesn't get with Grace (Due to Kenzaburou shenanigans) I think it's like... sweet? That Anna is metatextually portrayed as the most valid love interest for Grace (And we DO think that's a fair assessment). What Kenzaburou really did was basically unlock a secret route where you get to play Grace and lead her to a happy ending with Anna.
...Honestly, that idea is a lot easier to swallow when you kind of see it from the perspective of a player controlling a character in game. In the same way in universe "you" are controlling Anna to reach her route, Kenzaburou is doing that with Grace. Also, it means that this is kind of the most genuine and non player influenced Anna in existence: this is the truest Anna there is... being really really really obsessed over her girl best friend. Go figure.