Although some might see this as yuri (that ending panels could be seen as that but I think they were just embarrass on what the mother said) , the love between them is the love of two friends caring so much for each other that they each other as family (sister bonds). I think the kiss on the head near the end made it clear is wasn't yuri (same family kiss as the little brother got) but a family member ,a sister, giving comfort. Not to mention the MC keeps thinking about "family" the entire story and was never looking for a partner/girlfriend but rather a family.
Lovely story though on the importance on picking who is your real "family". Just because you're blood related, doesn't make you real "family" with those who don't treat you, care and understand you like a real family.