If she doesn't want to report it, then you can't really do it on her behalf, however that only applies to the harassment. It is understandable why she wouldn't want to report it (not optimal but understandable), but the bike theft is all on you. Go ahead and report the theft, but talk to her about it first. Tell her you will honor her wishes not to report the harassment, but you want to report the theft and the circumstantial evidence for them being responsible. If she still says she absolutely doesn't want you to, and you are not that worried about the theft, then you can drop it.