Spoilers for Rapture and speculation for the next episode.
So, according to the preview, Kara tells Sam she loves Lee, and Sam tells her to go to Lee, and she does.
Why would Sam do that?
1. He loves Kara, and figures if Lee makes her happy, yay.
2. He figures she'll get Lee out of her system.
3. He, being the people person he is, now gets Lee. And pretty much is gambling that Lee will send Kara back to him.
1 and 2, I'm ignoring.
It's 3 I'm interested in.
We know Sam reads people--EoJ, he saw the uncertainty in the crowd and he reached out and took them into the palm of his hand, and made them work for him. He's good on a one-on-one basis, too. Witness his easy manipulation of Kara.
Sam knows Lee, now. He's watched him lead people, watched him yell and scream and argue. He knows that Lee loves his wife. And that Lee loves Kara. And that Lee, for whatever reason, has some sort of honor--and now has doubt about Kara and her intentions. Doubt that Sam himself planted.
Because Lee knows he's not the first for Kara cheating on Sam--and whether it's true or not, it's not exactly something Sam can go and take back.
Not that he wants to.
Sam also, I think, knows that Lee wants Kara for more than just a short time.
He sends Kara to Lee.
Whether Kara tells him Sam sent her or not, Lee's doubt will be there. He can either have Kara until she gets bored with him, or he can tell her no, and stay with his wife (who he does love, though he's being an ass). And I think Lee is going to choose the latter option. Because, as I said, he wants Kara forever--that was the whole crux of him telling Kara to break off her thing with Sam in UB.
Sam is counting on Lee going for that option.
So, he'll get Kara back. A Kara rejected by Lee. He won't, I don't think, take advantage of that. He'll simply be there for her.
At least he didn't take over a third-world country, manipulate events, and let himself get shot just to get her back. But he is obviously learning at the Cable School of Manipulating Your S.O.
(this is all speculation, and possibly, sarcasm)