beta
This is why age gaps are too tricky but before we claim its grooming we have to acknowledge that they were kids when they met, its a fact that older kids can still groom younger kids but is that really the case here?
MC had never felt any romantic feelings for ML we clearly see it on the flashbacks, he has other problems in life, his father is beating him up because he likes guys in high school. MC has never once shown anything that could be considered grooming. He never had influence ML's life as a kid. Yes they were close but influence him to anything that could even be called grooming? Nothing was like that.
Never was at it shown in anyway that MC had gone beyond brother affection that could be considered questionable.