One of these can be the case with Raman -
1. He clearly is dumb and Simmi's puppet and doing everything just because Simmi asked him to (the most convenient way for cvs)
2. He is way too hurt by what Ishita did during Shanno track and is too blinded in his anger to catch any hint of Ishita being his wife or Pihu's mother and continuing this marriage only to hurt Ishita.
3. Romika only asked him to trust them and he is blindly supporting them having no idea what they are planning
4. He overheard some part of conversation of Ishita & Romika and trying to figure out what exactly the thing is and hence going with flow
5. Marriage is team ishita's plan and he clearly has no idea about it, but when proposed, he planned to use it as an opportunity to reunite Romika causing jealousy to Romi and making Mihika realise she still loves Romi
6. Either of Romi or Mihika communicated the marriage plan to him only saying that this might help them re-build their relationship without revealing the actual reason behind it, i.e. IshRa remarriage and he just agreed to help them
7. Romi/Mihika would have assured him to get Ishita by this way since he had revealed about his feelings for Ishita to Romi and also his dislike towards Ashok coming in his way
8. He is working all on his own alone, he simply wants Ishita to realise her feelings for him and reciprocate his feelings that he shared with her as Shanno because he must have realised then that even she has a thing for him somewhere. (memory loss continued)
9. He has come to know somehow that she is his wife, so trying to figure out entire mess
10. He has regained his memory completely and trying to push Ishita to the level that she reveals to him everything from Ananya's death
11. And the most surprising but least possible twist would be, he, whether has memory or not, completely trusts Ishita and both are planning together to knock Simmi Param down!
Phew! So many options are available for Raman in the entire scenario, hope the creatives don't take the worst way possible! My personal favourite would be anything that includes his memory loss continued and him chasing Ishita as he is smitten by her...continued from just where it was left after Shanno track. This will cover everything, the memory loss issue to be handled later separately, his effort for Ishita, a marriage only for Raman-Ishita k liye finally, his love-struck phase post marriage and a new love-love relationship starting post marriage and he gradually getting his memory back, and his redemption for his marriage decision...so yeah!
Until today his confused expressions and certain dialogues were indicating him to have a plan, but today's Raman-Pihu scene kind of confirms that. He would never take her to a private place otherwise just to teach her some manners. Had he not have any plan, he would continue shouting at her when she refused to accept Mihika like he did in that boarding school dhamki scene. But he stopped...n not just stopped but the scene clearly looked cut half-way...something like he couldn't take it anymore to hurt his princess and wants to reveal everything to her n calm her down. He either stopped suspecting Ruhi outside or he would have told Pihu everything in low voice so that Ruhi doesn't hear him and we will surely get to see the other half of the scene from where it is cut as a flashback when things are revealed. Hope this really works out, as it would redeem Raman as well and Pihu being completely unaware of the marriage plan will also be handled to a certain extent.