Ritsuko and Gendo

So recently I watched NGE along with Eoe, and I'm about to watch the rebuilds too. I love this series however when watching interesting videos on Youtube, specifically about Ritsuko, there's always the mention that she had a relation (most likely toxic) with Gendo.

However, I don't remember any implication of that in the series? I know Gendo was in a relation with Naoko (Ritsuko's mother) and that Naoko eventually committed suicide because she realized Gendo was using her.

So can anybody explain if Ritsuko and Gendo being in a relationship a conspiracy or is it something cannon in the show? Also if there are any scenes/implications in the series about this, could anybody kindly drop the episode and scene for me?

Thanks in advance pooksters.