I may be wrong but I think he is channel pick.
The only thing he shares with Riteish must be his name.
Rakhi's original husband is not willing to come on tv. This way she got one face to put in front of public.
There is no doubt about her marriage, but her husband is not ready to accept it in public.
Second, the channel gambled on him, which can lead to higher trps.
I think the channel will follow the lack of chemistry mismatch card between Rakhi and him.
I won't be wrong if they plant divorce seeds in the audience's mind.
This will generate higher trp, and Rakhi will get way to end her marriage with original Reitesh.