Trip her and say it was an accident all though it was on purpose.
Then she has to choose you or her boyfriend.
I would confront the girl or warn your boyfriend
if i where you i would tell the girl that likes that boy that he has a girlfriend.that is what i would do.
She already said she likes you.
If she shows interest ,or complains about her boyfriend to you.
that she likes you
She likes you and that other guy and her boyfriend but does not know who she likes best.
* * *
If the man has diabetes.
Treat her better then her boyfriend did and she will see you are a better person
The one that likes you without a girlfriend.
just try to get her to back away