Don't think too hard on it. Kat didn't actually want to be on his stream (or, at least, didn't want to be on there for like 3 hours doing absolutely nothing)--hence why she didn't talk and literally had earbuds in pretty much the entire time. She eventually got tired of it, told Phil to go fuck himself, and peaced out to do something that wasn't watching her 36 year old manchild boyfriend bitch at video games while half-assedly pretending to be Bob Ross and repeating the phrase "happy little accident" over and over. Because Phil can't ever admit that maybe he fucked up and wasn't actually attentive to her, it clearly was Tevin's fault because he's obviously a detractor troll hivemind leader.