I think this is a very clever move by the creatives of the show, and emphasizes an important point that until Yash and Arati come to a harmonic understanding between them, which cannot happen without emotional maturity, their relationship will continue to be vulnerable, and seek expression primarily outside themselves. Their dynamics, in a sense, will continue to be enacted in the open, thereby further weakening their tenuous bond by constantly being the potential target of everyone's opinions and interference, Boa being a case in point.
When Papa Cas allowed them in the house, after the most recent fiasco, it was with the tacit understanding that they would grow to make decisions together and no longer subject the entire family, including the young ones, to their "ashanti." But that clearly did not happen, with Arati going into great details about the pregnancy complications in front of the whole family before disclosing them first to Yash. Therefore, it is good that Papa Cas threw the decision of how to proceed with the pregnancy back on to them.
It will be interesting to see whether this dynamic will change with the upcoming Prashant disclosure, or if we have to wait until Yash is able to fully commit to Arati.