My coworker offered to blow me?

I work as a cook at a middle range resturaunt and tonight as i was closing, it was just me and a female server (were both 16-18 and our manager left early) and we usualy flirt with each other friendlylike (my girlfriend, knows and doesn't mind). Tonight though, she came up behind me and grabbed my penis through my pants. When i pulled away, she got really close to me and told me if i wanted she would blow me and that she's really good at swallowing.

I've already told my girlfriend because i dont want this to affect my relationship. However Im really worried about my coworker because she's never acted like this before and she's seemed off and distant lately. So my question is what do i do, if there is anything i can do, to try to help her? My girlfriend is being suprisingly understanding
My coworker offered to blow me?
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