like I really do feel like there's a "rapist/rapist adjacent" eridan sexual harassment nice guy affect thing going on when people perceive him which makes sense insofar as he flirts hard and likes his girl best friend, but I don't really think him fitting this way people perceive him is accurate at all to how he actually acts in similar ways people misperceive his whole "genocidal" shtick as if he's not play acting something that's in complete opposition to his core trauma and daily life. so I don't always agree with dark explorations of Eridan that go from this sort of perspective.
however he is like. an ultra privileged kid in a society based on slavery, oppression, and fuck-or-die reproduction. I don't think he even particularly would be bad compared to others in his caste because of how much exposure he's had to others from a young age. like he doesn't really buy into this shit he's spouting, I'd say even comparably to other high bloods despite his Outwards Hemocasteism. But that doesn't change how he has not go any good framework on how to have healthy relationships or exist within the society he's in without perpetuating it, up to the point Feferi has a chance to overturn it (and then perpetuate that paradigm).
So like I absolutely think if his partner were someone he had total control over who was terrified and utterly dependent on him, he wouldn't exactly register how to handle it besides "put on seadweller maybe say some slurs" and trying to treat them as a complete equal. but they're equal in a world where things like consent and healthy relationships are not something you can access how to portray easily so less understand the complete horror and weighted balance of such intense power dynamics.
this all to say. no I don't think eridan is some sexual harassy creep for being bad at flirting at six. yes I absolutely can see him doing horrific things due to perpetuating the violence of the system he's in even if that was not his goal including violations of boundaries and consent. which is important. because most people could.