Let her in on the secret, because, well, I'm fuckin' her best friend.

Threesome, maybe?

Tell her I'm not? Pretty straight forward.

>>10518
if only situations like that were that simple.

Ask her the reasons she thinks so.
Then depending on the situation I would reassure her or I would prove her that she is wrong while reassuring her in an affable tone so she can feel my love for her.
If the situation requires so I would do something to deepen our relation and/or mutual trust.

Without seeming desperate, I would reassure her that I'm not, and that the thought would never even think of doing such a thing. I would somehow prove to her that my love is only for her.

>>10520
This. My waifu is generally rational and easy to reason with, so I'm sure I would be able to convince her of the truth.

I'd honestly feel pretty hurt after being falsely accused of such an act, though.

I'd push away teh Rei...

It can't be helped. Otherwise, things will go right down the drain.

I'd genuflect, then proceed to cry and beg her to believe that that is completely wrong.

Surely, that would bring her to see her allegation as false and prove my innocence.

I would laugh at her face and tell her none of her friends has bad taste as she does.

I guess that she´d be able to find out very quickly if I cheat on her or not. And if I did...i´d have no time to explain anything.

Try to calm her down, and work out the situation logically to prove that I'm not cheating on her.

Chihiro works hard to protect the ones she cares about. If I ever betrayed her, not only would I hate myself, but...it probably wouldn't reach yandere levels, but it'd still be pretty bad.

I don't know why she might believe that. Maybe the other idols started some horrible rumour.
I'd probably buy some of her favourite things for her and just try to show her how much I love her so that she can realise that I would never ever think of cheating on her.

With certain girls, I doubt she'd even mind.

However, if it were a conflict-of-interest issue, I'd gladly do what she deems necessary to prove me innocent.

"You could Spark or Stardust me all you want, Marisa, but you're making a baseless accusation."

"Seriously, Minami? Okay, uh, no, that's silly. I'm not. And I never would. Beyond that, what do I need to do to prove to you that I'm not? Look, I can understand why you'd be upset, but the fact is that I'm not cheating on you. That'd honestly be one of the biggest mistakes I'd ever make, and you know that."