Could you please help :(. ?

I will try to make this as short as I can. there is a girl I know that I like alot. she knows I like her and she seys she likes me back. however, she lives rly far away, and it's pretty much impossible for us to get together as bf and gf. we keep in toutch with fb chat btw. also, she has a bf. she and her bf have broken up more than once and they have just gotten together again, and I'm worried that he is going to break her heart again. how can I tell her this without just seeming jelous?