I think people aren't reading between the lines on this. From MLs perspective, his relationship was getting better with MC, MC was starting to "open up" and "rely" on him more, but ML just realized, it was all because of the pregnancy hormones. Did MC even like him? Or was it just because MC was pregnant? That's what angered ML. He doesn't know what to believe anymore, and he can't take the rejection that might come if MC "finds out that his 'love' and 'clinginess' were just pregnancy symptoms". Or at least thats what I took from this chapter