Summing up the story so far, I like the direction its going in and how it has developed even though "drama" is about to set in again.
Previously, Eugene and her step-brothers, saw her as nothing more than a fake that was freeloading off their parents grieving for the loss of their real sister which then slowly dissolved into a situation where Hari believed it may have been better to die on the streets then be treated as a "replacement" her whole life again.
Coming to terms with the loss of their sister, and that it was not just them suffering from this situation but also Hari, Eugene and her step-brothers decided to treat her as her own person but also as "family" with the loss of their parents.
Eugene decides to step-up and throw away his childhood in-order to become the family head and protect his "family" from now on. The loneliness of this ordeal is understood mostly by Hari, where she regularly writes to him over the years to let him know she's still there for him alongside his brothers.
Not meeting Hari for a few years, Eugene accidentally becomes enamored by the passing sight of girl who bumps into him only to then find out its Hari giving him a complicated feeling. Though in the back of his mind he's aware that Hari is "family" now, he can't really forget she also not his real sister by blood. So in-order to perhaps stifle these mixed feelings Eugene is starting to distance himself from Hari in-order to cool off and remind himself that she is family to him.
How the author intends to develop this situation going forward is interesting, because they could either have Hari inquire why Eugene is being distant and he shifts the topic elsewhere or Eugene take a mature or immature proactive approach where he annuls his engagement and pursues Hari to follow his real feelings, or speed up his marriage to lock himself into a situation where he can't pursue them anymore.