First of all mani had no right to slap raman, and had no right to interfere in Ishra matters. Who does that! any decent friend know his/her boundaries and by hitting Raman, he had insulted Ishita too as he didn't respect him as Ishu's husband. Shockingly Ishu allowing this to happen!
When Ishita is so quick to stop Raman from slapping Adi why didn't she do the same thing with Mani? At least viewers can undestand a father slapped a child due to his silly tactics but no one can understand a friend slapping your spouse, since they have no rights at all. It is immoral and disrespectable. In a real society it would question Mani's relation to Ishita and on her character. Where the logic in this track? Just nonsense. I don't approed the way Raman slapped Adi but some parents do this as a punishment to wrong behaviour. Mani slapping is insulting and uncomprehendable.