Hi! I don't know how I got "See it All" but I did try checking out all the choices in the game. It will be helpful too if you got Roomie's ending in all Luxiem boys' routes. Hope this helps you!
In order to get roomie's ending, you need to choose a bit of bad choices (let's say 4 or 5?) in any route. It's kinda like the "just bros with a Luxiem member" ending. I usually choose bad choices in the beginning of every route so I can balance it out in the end with good choices and get roomie's ending.
(Good luck when you get the bad endings because my heart broke many times when I went through them... T_T)