Maybe it depends? Like his level of embarrassment/arousal. If the blush is really dark and spreads further on his body, then he's really embarrassed or aroused. If it's light, then he's probably only mildly flustered or something .o.
Imagine he is actually embarrassed because of something but the blush just wasn’t clear on his pale skin, and it made him look more serious/annoyed than he supposed to be
When aroused, or maybe after done the intimacy, the blush spread through his body while he panting in batted breath is just so darn adorable omfggggoooooshh aaahhhh











