All this arguing over "is it yuri or not" is ignoring the key point of this relationship: it's not about the two of them. It's about the two of them and the hole left by Taishi. They both have their own situations regarding family, and Taishi was a huge part of their lives as a result. Now that he's suddenly disappeared, they're both looking for something to fill that gap, and the easiest person to do that is each other. It's not necessarily a healthy relationship, and the author has the potential to really go more in depth with it than just "yo ladies lovin' each other". Whether or not that's where it'll go, who knows, but I think expecting it to just be a normal SoL is really selling it short.