Thinking now, I believe that Muskaan was more loyal to her love than Riddhima.
Muskaan and Rahul comsummed their relation, and they weren't even married. It's sad that Rahul due to his impotency didn't want to through with the marriage. However I think muskaan is a strong girl. After having done what she did, she still didn't bow down to society, and marry some idiot. All that we know is that she is in Patiala practicing medicine (though her family prolly lives in the illusion that she and rahul still stand as a married couple). And throughout she waited for Rahul all the time.
On the contrary we have this super confused brainless Riddhima who didn't even wait for Armaan (not even a year!). After Padma's fainting. Riddhima could have left a letter and gone somewhere secretly. She could have approached Billy and coaxed him to help her without her parents knowledge. And still now she hurts Ammy! Not fair. She should feel every pain she inject on Armaan.
If Muskaan was in Riddhima's place (but obviously Muski dear has more brains to avoid landing in such a mess in the first place!), she would have been decisive. That's one thing I've noticed about the Punjaban! That kudi knows her mind. She wouldn't have married some idiot, or even if she did, she would have asked & aplied for an anullment as soon as she could have!
And one another hand we have Sid falling in and out of love. Someone explain to him the difference between: friendship, attraction, crush/infatuation, duty, and true love. That lad is so confused.
Someone other than Shanky perform neurosurgery on the creatives. They obviously need one if thy are hell-bent on killing the theme of DMG!