Loid's plan making my Twiyor heart sing!
Entirely based on chapter 131 of the Manga.
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When Twilight contemplates that he can swap with the actor by disguising himself as the actor, there are only two possibilities:
either (a) Yor doesn't know that it's Loid and not that actor, or (b) Yor knows that it's Loid and not that actor. There's obviously no 3rd possibility here.
So, while Twilight has not analysed yet WHY he considered swapping places with that guy, WE definitely have analysed it.
Let's consider both scenarios (a) and (b) and what would be achieved from them. In either scenario, he's not planning on letting Yuri know. Because that would be risky. So he's not doing any of this for Yuri or SSS' benefit.
Scenario (a) Twilight swaps with the actor and let's Yor know (while hiding from Yuri, of course). But why? Because Twilight believes that Yor would rather kiss him than the actor. And that she would be relieved and less uncomfortable if it was Loid instead of that actor.
Or
(b) Twilight makes the swap without telling anyone, including Yor. But if Yor doesn't know, then what is the point of Twilight swapping? Yor would still believe that she's in a kissing scene with that actor. So the only people who'd know that she kissed Loid and not the actor would be Loid and the actor.
So, Mr. Twilight, you either believe that Yor would be more comfortable kissing you than an actor (even though she mostly kicks things when you get close) or you just didn't want her to kiss someone else.
While Yor wonders if Loid was jealous and thinks he wasn't, we can't be sure. It could be a or b. But, from what we know, both scenarios are good. He’s either sure that she's happier with him or he's jealous. And we know one thing for sure, that he's protective of her.