Those photos are clearly depicting a couple, not just close friends. The right three photos are 100% capture of a couple in love. Saki's expression on the top right photo says it all about Saki herself. Kanon's expression on bottom right says it all about Kanon herself. The right middle one show mutual affection that only lovers express. The left three are more like best friends that never fight and deeply care about each other. The senpai really knew how to capture people. So the photos show that it is a romantic love and also close friendship relationship, the best type of relationship between a couple.
Saki may come out to her mom as a way to test her own courage.
Kanon may now somehow guess why Saki wrapped around her waist from behind and said things. You only do that to someone you love, certainly not friends.
This manga is peak.