About tense~

She is surprised how much the personal/emotional relationship (the "chemistry") between herself and DiCaprio, which began when they made the film Titanic together, still persists ("sticks").

Film makers (and television show makers) often talk about the "chemistry" between two leading roles on screen.

You feel like they really are in love, or they really do have the relationship being depicted. (It could even be mother/daughter, or brother/brother, or mentor/protege, not just romantic.)

When you see these two people on screen, it feels right. That's chemistry.

but why she used the negative form...?
she can say i had realized……since the……
what is the defference?

Winslet is talking about her reunion with DiCaprio. She is saying that before this reunion she hadn't realized how much the chemistry would stick. The implication is that now, after the reunion, she realises that the chemistry has stuck, and she is a bit surprised by this.

thanks very much!!!before this reunion she hadnt realized how much the chemistry would have stuck ?and
why not saying she didnt realize…… ?

The past perfect, in this case "hadn't realised", is used to go back further into the past, relative to some reference point that is itself already in the past. In your example, the reference point is the time of the reunion, when she realised that the chemistry still existed. The time when she didn't realise was before this.

However, "didn't realise" in also possibl

thank you very much!i got it!