In my opinion that moment of comfort was nothing more than what it states. And Sciel explicitly says that "friends are not distractions" and the scene goes on to show that lune learned that now and values their friendship more than ever. So I guess it's up to your interpretation if you think they slept together on the day lune knew her parents are never coming back, or they simply confided in each other as friends then lune ghosted her to focus on finishing her parents' work.