If people see this as subtext, they clearly don't know what subtext is. These characters are not family, they are not friends, I don't even think they're really classmates. But the protag says, explicitly in text, "I love her." That, my friends, is not subtext. It doesn't need to be a physical expression of affection, and it does not need to be reciprocated. If you're looking for subtext, look at any of the major "yuri" series like K-On!, Final Fantasy XIII, and the like. They have heavy subtext, where characters are close and whose situations would be viewed as romantic if the characters were opposite sexes. This story, regardless of how satisfying the ending is or isn't, is yuri. I'd say we're rather fortunate to live in a day and age where there are enough yuri works to argue about whether or not it's gay enough. I used to be satisfied with shows like Kim Possible and Bleach, filling in the subtextual blanks with fanfiction.