I think Byul meant something like "If only I could like my lil bro back, then everything will be good.
He won't be hurt and I won't be ignoring him like this. But the problem is I don't have any romantic feelings for him." Which is being shown for the past chapters as he tries to resolve the issue between him and his bro. I don't think Byul would love his lil bro back though since he already has some sort of "feelings" (unaware tho?) for the BL Motel owner.
See that's what I was thinking too but like shouldn't your first thought as a sibling be like "If only you didn't confess wtf"
Can someone explain what he meant by if only I could accept my younger brothers feelings this would be easier to me cuz I really hope my interpretation is wrong