@sirflimflam denial is powerful. I think Itsuki is trying to protect herself. To have gone through such a life-altering change: having to give up baseball, having to move, losing Ritsu--that all must be really traumatic. So, I think there is a subconscious part of Itsuki who wants to keep her distance from Ritsu because it's painful to be reminded of the past, or maybe the denial stems from fear of rejection. Ritsu has given her opportunities to come clean, but she resists. I'm convinced that is for her own sake whether she realizes it or not.
It'll slowly develop, but I think she'll need to fall for Ritsu on her own and realize her feelings before she outs herself...unless Ritsu figures it out first.