In what episode do Tyler and Caroline get together and become a real couple?

I think its 3.01, The Birthday. At least, this is the first time they sleep together and they act like a couple in future episodes, so...

I am rewatching the whole series I'm pretty sure it is either the en of season 2 or the beginning of season 3 because I know tyler kisses her and I think she is dating Matt and she goes gosh everybody just needs to stop beijar me! lol so I knows it is on between there. 😄 amor to help people!