But that would be too much right ? I don’t have any proof that it was harassment , could be just normal drinks I also offered her one , but this guy was certainly trying to touch her shoulder hold her hand , and call out her name multiple times
It isn't your responsibility to gather proof or to make a career-impacting decision about these two people, that's for HR, legal and senior management to deal with, and they have the tools and processes to actual investigate. (Check your employee handbook, companies I have worked for in the past require employees to cooperate with HR investigations and refusing to comply can lead to termination). If there really wasn't any problem then HR will take no action (they don't want to get sued for wrongly terminating a manager either).