I agree with both Fuzzy and Shalu just read, Yes there is no way any ONS extra marital affair between DM and that Dr? 
DM may have met her years ago and they became friendly all innocent someone to talk to and she obv has a held a hidden torch for him but its obv this will and was never recipricated by our DM if she made her advances, he has values and principles we all know that DM gets what he wants but nothing as disgusting like this and like I also said it would go all against what he believes in and all the surmons he gives to everyone about marriage, truth, justice, sanskar, stan, lies, cheats these are like bible words and thoughts to him and to rule he would follow those rules and make an example to his children and villagers and as Shalu said he never had relationship with Santu after their 1st marriage because he thought he was cheating on his dead wife Subhi and only whole heartedly accepted Santu as his wife emotionally and physically once they both accepted eachother 100% as husband and wife after their 2nd marriage so there is no way that he could go and cheat on Santu have a relationship with another woman even if he was lonely, on the same wave length as her or thought Santu did kill Arjan. DM is a one off character of Ekthaa's different to all her other leads who cheat and have children by other women most of those characters were modern guys DM is an old fashioned village guy, he wouldn't leave his family relations lil children and go make relations with someone else no way. I hope Ekthaa keeps to DM's true character, she will if she wants this show to survive.
The other thing is DM specifically said to the boy and Dr? child is like 9-10yrs so if he had any physical relationship with this Dr? the first thing that would spring to anyones mind is, oh oh, its not mine is it ??? š² and DM didn't seem to be like that at all when talking to the kid or to the Dr? DM just seemed annoyed to see this woman and she too shifty so its gotta be SANRAJ child, rude attittude and hands on hips of DM and maturity of Santu, this must be their child. Dr? has her hidden agenda, like i said wish she would trip out the train and eat tar! I too wish we get the old DM back with humor naughty romance and less white moochi.