I'm guessing you are looking at images and didn't actually read the scenes? They don't make out in any way, shape, or form. This image was from a scene where MC accidentally kisses Emily. Emily turned her head expecting a hug when MC was trying to kiss her cheek. Both characters talk about it and MC has his dramatic "I'm going to die of embarrassment" performance.
However, if Emily buys the motorcycle the MC can kiss Emily on the lips. Again no make out session, read more as 'out of excitement for getting a motorbike from mom'. She teases MC with his "I'm going to die of embarrassment" performance , from above, perfectly.
Is a kiss on the lips incest? Then I guess a lot of parents and grandparents are committing not only incest, but also statutory rape, with their younger kids.