there's something going on
(1) go on可以表示“发生，进行”
(2) there's something going on between sb.“某人之间有暧昧”
There's something going on between Heather and Wesley.
I think that there's something going on with her and a boy.
there is chemistry between sb.
(2) there is chemistry between sb. “某人之间相互吸引，某人之间来电，某人之间有火花，某人之间有暧昧”
I think there's a very real chemistry between them.
Well, we do have chemistry.
(1) flirt “调情”
(2) flirty “调情的，暧昧的”
(3) flirty messages “暧昧信息”
Last week, I picked up her cellphone thinking it was mine. And I accidentally read a few flirty text messages.
A boy sends you flirty texts. Doesn't mean that you have to text him back.
flirt with sb.
(1) flirt “调情，打情骂俏”
(2) flirt with sb. “与某人调情，与某人打情骂俏”
A: You flirted with Sherlock Holmes?
B: At him. He never replied.
He's totally flirting with you too.