
Here, an explanation.
https://www.mangago.zone/home/mangatopic/19223991/

That's a God, not a human being. He can literally turn into a snake, travel in the ground super fast, and many other things. Being able to split is his most common power. I'm perplexed that it's the one that surprises you.
And what do you mean MC is blacked out on sex? If you're talking about his facial expression, that's the author's way of drawing the fuzziness of being drowned in pheromones as an omega.

Ok but if he's a God and he can give his other personalities a physical form then like what's the point of being a God with split personalities where each one has to fight over whos in control of the body. I know its nitpicky but I like when each personality does their own interactions with MC. I just feel like the smut plot armor is strong with this chapter.
Also I mean where it seemed like MC was confused during sex like he noticed something was going on in the background but then decided to ignore it. He's like

The facial expressions are fine but it seemed he noticed something and it caught his attention and he was confused and then chose to ignore it I think the cliffhangers are getting to me. Maybe I'm forgetting that he can split? I mean we've always seen the other personalities in like reflections and shadows and figments of his imagination but I feel like this is the one time where they're physically real?

You're misunderstanding a key element. It's not "a God with other personalities". They are ALL the same God. It's 1 God split in several parts, not 1 God AND his other parts. This is very important for you to understand. They're ALL one entity divided by dissociation, which is why they're ALL personalities and not independent entities.
The very reason why they SOMETIMES fight over the control is because they're the same person.
He didn't " give" his other personalities the body. They agreed to split the body, just like Naruto when he uses multiplication technique: they are all Naruto, but HE as a single entity decided to multiply HIMSELF into different forms. Splitting his body TEMPORARILY doesn't mean he suddenly created an actual other Naruto, even though they have different forms.
Same thing here: they all share the SAME body, so for ANY of them to do anything with it, he has to be in control without the interference of others (sometimes they just can't interfere because they are not in control of the body, sometimes they could but they just agree or give up on fighting it, which is what you saw in the latest chapter).
In this case, you can see that Mean Mugo is in control, but Monster Mugo decides he wants to join in, and the ONLY reason the body doubles is because they AGREE to some degree: Mean Mugo doesn't mind, and Glasses Mugo has given up on stepping in.
Think of the control as an expendable door: if no one is blocking the door, then everyone can come through it as they want, and if everyone agrees to change the door style and no one is keeping the others from it, then the door style can be changed easily. If someone is fighting the change of style, then either he's strong enough to stop others from doing it or he's not.
The roles I explained in the link I gave you help you understand why in some instances, a Mugo overpowers another one.
"multiple personality" stories are inspired by Dissociative disorders. So if you really want to understand the Mugo, I recommend you research DID, there are plenty of channels explaining how it works. You can also read about it. The more you inform yourself about it, the easiest you will be able to understand this story and even other stories that include multiple personalities.

I think you're making the mistake of thinking that the Mugo were the MCs imagination.
As I said, they are all the same God. When they take control, they decide to change the head to match their own characteristics. Sometimes they will completely change the form of the body especially when there's a strong switch: that's what you saw when Monster Mugo got too hungry.
So MC is never hallucinating, the Mugo changes shapes. He doesn't realize it at first because Monster Mugo is literally just Mean Mugo with hair down, and Glasses Mugo is literally the same person with glasses. If someone "changed shape" like that, you Wouldn't understand the relevance of it right away either.
So, he notices something because THERE IS genuinely something. When Naruto splits and his enemies see the other Narutos they're not hallucinating, it's happening in front of them. Again, the reason why the body can multiply itself like that so quickly is because none of them is fighting it.
If you remember, there are several moments in the story where the head changes rapidly between Mugo and even becomes black: that's an example of what happens when they fight for control and/or disagree on what to do with the body.
I'm so confused