as of now, i think she is just too insecure...her life has been full of problems...firstly the scandal with Param...then her mother's illness...later betrayal by Romi n her pregnancy...it mustve been tough for her to go through the pregnancy alone, where mostly even her mother wasnt there to guide her...
and because of all those circumstances, either she doesnt trust anyone, thinks that everyone has a motive to do something good...and she feels she need to be extra alert n doubts even the simplest of gesture...like Ishita giving her the clothes...even this misturst shows the lack of guidance during her pregnancy...as handing over old clothes to new-born's is a common practice, so that the baby doesnt develop rashes or bruises due to new clothes...but this info is given by the elders to the new mother...which Sarika lacked...n hence doubted Ishita's intentions
so yesterday she did instigate Romi, but mustve realized the extent of damage when Raman Ishita left the house...hence she requested Romi to stop Raman...if only she herself had stopped Raman n apologized...but then she is immature, hence she didnt herself apologize to Raman...
so i think majorly, its her insecurity n immaturity at play