That was a joke (also I don't remember any insertion actually happening), but you'd be surprised; women come in all types, mindsets, personalities, etc. particularly when it comes to things like fwb or hooking up. In this particular situation though, if the female lead was aware of this I assume they would be simultaneously jealous but also not honest enough to disclose why they are jealous. I'm kind of glad this story is cuter than it might seem based on the premise + Japanese societal norms (at least as depicted in manga) but simultaneously maybe some part of me wants it to be a bit more nuanced. At the same time, I also don't want it to go full smutty romantic drama, I feel like it's hard to find that balance.
