@Entryhazard Well, if Tendou wants to be seen as an equal, she has to work for it. As Tachibana said, she already done it twice, so she might be just there soon.
The tennis thing is definitely a part of his problem too. However imo the difference between Tendou and Tsubasa is that Tsubasa was an internal distraction to tennis (as she plays tennis and is interested in it, iirc Tachibana already knows Tsubasa is healed? no?), while Tendou is an external interference to tennis. That's a slight but important difference, you want to solve internal problems in your life asap, while you can just turn a blind eye to external problems most of the time because you don't meet them during the time you do what you want.
Maybe this is why Tendou still has a chance with him if he decides to because (poor example incoming) he can like sleep 2 hours less in favour of tending Tendou for 2 hours a day and it wont take time away from his path on tennis. Hope you got the gist of what I want to say with my poor example.