Firstly, dev made her promise that they would never leave an unfinished fight and walk away which i think is very important in any couple...so mature for him to do that .
And secondly he offered all of him today..his anger, mood swings...he is a difficult man to deal with...so is she ready to be with him in this relation?...and boy her answer !
She held him back, hugged him from behind and took the dive with him...she is ready for him, to be all in with him...
And finally they sealed it with a hug in the rain...beautiful !
These two things will be the foundation of their relation in the future...i think this would be the answer to dev's proposal...even if she hasn't said the words yet...their relation just began