Since we do not no his thought it is hard to judge what he is thinking. And can you please give examples of those nice things he did to Eri without having Tenma in his mind? Yes, he is changing his attitude, but he is still far from love. Example: in ch208 thinking about if he can go or not hes says: "I can you a break". Not very emotional to me. And his facial expression is far from "exited" and more like "Oh well".
Harima's become a bit of a wildcard in recent chapters, so we can't be too sure how he'll react to everything anymore. We’re not shown what he’s thinking as often before, and almost never when his thoughts concern Eri. Nonetheless, Harima seems to be changing his attitude towards Eri slightly. For example, earlier in the series, Harima would have turned down Eri immediately if she asked him and she would have had to tried harder to convince him to come with her to the oyster bar. Also, during Chapter b43, Harima hesitates when Eri asks him to go with her house when the alternative is going to Tenma’s house. Then add the times Harima has gone out of his way to do nice things for Eri (without Tenma as his ultimate motivator), and that’s enough evidence to argue that it’s possible Harima unconsciously likes Eri and any time he denies it is just his ego mentally suppressing this knowledge from himself.
If that’s the case, Eri just needs to do something strong enough to cut through his ego in order to make Harima realize this. A confession just might be enough to do this. To simplify my message, I used math:
Sigmund Freud FTW + Freudian Psychology supporting Flag = Flag FTW
... And just to make my Freudian psychoanalysis of Harima complete, I’ll mention that Itoko serves as Harima’s surrogate mother figure, and that Harima treats Eri and Itoko very similarly, implying that Harima views the two as similar. This leads to the conclusion that Harima views Eri as a surrogate to his surrogate mother figure. Thus, due to the Oedipal Complex, Harima must love Eri.