OK, well if you played to the end, you would know Bruce still has feelings for Jane and unless he lied to the MC, he DID NOT encourage his ex-gf/childhood friend to send him the topless pics, that all the heavy flirting has been coming from her, which she corroborates if you take the escort job and meet with her. So essentially, you do in fact cuck your father unless you plan to work with her to change his mind about Jane and pursue his ex-lover instead.
Secondly, are you really that freaked over 2 people in a relationship, sharing a bedroom for fucks sake actually having sex? I mean I guess it's one thing to assume they are intimate and quite another to hear their lovemaking, but again, the MC didn't exactly see anything, he just heard them.
If you read the Dev Notes, he specifically outlined the relationship dynamics with all the L.I., particularly those already in a relationship as just being temporary until the MC decides he wants to pursue them, ergo, no NTR. It's just one scene, but if that is all it takes to destroy your immersion or interest, either don't pursue her or maybe this game isn't for you.
I wouldn't plan on regular content updates anyway as the Dev is moving abroad to finish his education which will be a 4-year commitment. He did say despite that he plans to finish this VN via Itch.io updates since he will suspend his Patreon and Subscribe Star pages but unfortunately due to his new situation he may not consistently have the time to put out future updates on a regular schedule.