Yes, honesty wins the day.

Starfire explains how this started- with you staring at her tits.
How she wanted you to play with them and how she really enjoyed this new sensation.

She explains how things escalated and how she, herself, brought up Raven. How you offered to help her with her query.
This surprises her teammate, who likely assumed that it was you- the horny guy- who tried to get himself a threesome.
I mean...you did, but you were subtle, at least.

"So it was your idea to do...what we just did together," Raven asks.
"Yes, I've always wanted to be more intimate with you."
Raven blushes outwardly and swoons a little bit internally.

"So...what was the plan here? I mean, what was the endgame," the Goth Titan continues.
"She wanted to have this experience with you. She wanted to share it with me."
"And what did you want?"
"I mean...you're both amazing. You're hot and kind...who wouldn't want to be with you?"

Raven blushes some more...and moves her hand to uncover her tits.

"So...did you enjoy the show?"
"I think you can see that I did," you reply, looking down at your crotch.

Yeah, Superhero outfits don't exactly make it easy to hide that reaction.

"I must admit...while I like Beast Boy as a friend and I know that he likes me like, well, you clearly do, I'm sure that he's mature enough just yet."
You can always be with both of them if you want," Starfire says, chiming in.
You nod...and she blushes even more.

"Wow...alot to think about. I think...I want to have some fun right now."
"I too want to have the fun," Starfire says.

You smile and begin to take your clothes off.