What the preview doesn't tell you (thus what I won't reveal here ... I'm a "good-boy!") is why Chuck is a serial-dater. In short, (like Dane Cook), he's a good man ... one who knows that the world owes women more than we men can ever repay.
Chuck isn't exactly giving them 'his love' though, what he's giving the women is ... the reason his name is "Good Luck Chuck."
Jessica Alba's in it; you've seen her and Dane Cook in the previews, so you can guess how the movie's going to end. (Sure, there's a little 'suspense' as to how they reach that ending; but it ends up exactly like you thought it would.)
All-in-all, it's a good reassurement that, "If you set her free, but it's meant to be; her heart will pull her back to thee." (This is why I don't write movies: because I turn and tell you the overall meaning rather than teach it to you slow like every good movie does.)
Granted, there are definitely more lessons in this movie than I can appropriately name here (what friends are good for, what women always want to hear that you should never say, etc.) but those really are lessons you should learn slowly.