Don’t worry it’s really not like that and I recommend you continue reading!
I can sum up our main characters like this: Megumi is the romantic and it takes him a while to realize he needs to be direct to his partner. Tsugumi is animalistic and slow, as in he will go with the flow as long as it brings him benefits but he doesn't stop to think about the feelings involved until someone else points it out to him.
I would think of chapter 4 as the two being curious, after establishing they were on the same page. Yes, it could have been handled better. But Tsugumi acts now and thinks later while Megumi had enough personal checkmarks filled to equal green means go. As tensions rose, they were sharing the same brain cell.
Just started reading this and I can’t help but feel uneasy about what happened in chapter 4. I know Tsugumi told Megumi he liked it later on, and even argued with Megumi when he called it rape. But the author really did portray what looked like rape in that scene. If this was not an omegaverse, no doubt most everyone would see what happened in chapter 4 as rape. I know the author was trying to portray the enemies to lovers trope, but I wish they at least showed how Tsugumi did enjoy it in that scene. Even just some thought bubbles showing Tsugumi’s words not matching up to his desires. It just makes me sad, especially after reading Kiraide Isasete and seeing how the alpha in that story handled things in a parallel situation