Of course he did. This is why he's an
incredible male lead. After Kannou Sensei's lead was executed in the name of Jousei Spice, he's like top fuckin' two older male leads in an older male/younger female romance that are active right now.
Ishizumi cares deeply for her. But he is much older than her, is her subordinate, and feels a debt to her father. He has decided that his role is to act as Izumi: the man she doesn't fully know to support her directly when she is the weakest. He won't take advantage of her misdirected feelings, and his future hope is that one day she'll find someone who can actually do the job in totality and for real.
HOWEVER: what made Reina fall in love with Izumi, what KEEPS drawing her closer, isn't the idea that he's a man her age(or younger) or that he's well placed or that he's even
successful. It's that he listens to her, sees her try as hard as she does, and values the things in her that she doesn't value in herself. Ishizumi isn't pretending to be anyone else when he's Izumi. He's just not pretending to work for Reina. The most powerfully romantic things he's said have all been things he firmly believes, the most powerfully romantic actions he's taken have been ones he did sincerely. The first night, the spark that ignited this, was him seeing her in despair and telling her that he sees all that she's done. He tells her to keep going because he'll be there to help her. This wasn't a line, it was his Honest 2 God feelingz, which is what made them HIT as hard as they did for Reina.
The reason he keeps doing this is fascinatingly layered, because it's not totally selfless. He
is scared that he'll lose this connection. He's
proud and
honored that she trusts him so much with her heart. It's a priceless gift that he is prepared to give away, but not because he doesn't value it. But because he values it
so highly he doesn't think he deserves it. It tears him up in a convincing and interesting way. A lesser writer would have him be giddy and nervous about losing it, or stoically weathering the emotional storm of Reina and hoping that she'll find someone better one day. But he's engaged, emotionally impacted, and is filled with guilt while acknowledging that he's doing something useful, important, and something that he likes to do.
Reina, for her part, has been
absolutely clear about what she's found so powerful about their connection. She's been consistent in her desire to connect more. She's told him that it's HIM that she likes, not anything else. But Ishizumi can't believe that for a very good reason: he's not exactly trying to hide himself, he's not exactly being subtle, and she's so drunk when she meets him that she literally sees him the next day and can't remember it. Her earnest, honest, and clear speech here and her clear declaration that she knows him no matter how drunk she is when she meets him? It's undercut with humor: she made most of it to a tree. Even if Reina believes what she's saying, even if Ishizumi believes REINA believes what she's saying... he has every reason to deeply fear that revealing who he is will ruin everything. It's the best sort of misunderstanding: you
can see it clearing up. But you
know why it hasn't.