Well I am gonna put this in spoiler tags just in case and so it will have spoilers for Episode 4
I think it either ends with Lee sacrificing himself to get clem and maybe a few others on the boat and season 2 starts from there. Or option 2 is that at the end you will be presented with a couple of choices. That you can either have her go with Kenny or that she can go with Christa (I have the feeling Omid will bite the big one after being away for almost all of the episode) or with the Vernon the doctor. I think that if you didn't drop Ben he will go out in a blaze of glory in Episode 5 maybe saving one of the choices.
And a very unlikely ending is that they find a way to save Lee from becoming a zombie but handicapping him so Clem has to do more in season 2.
I don't think they'll end both Clem and Lee, but if that is the case I am hoping for a "just leave us" option where you can decide not to kill yourself and clem so you can at least be together in zombie form 