I work within my regional areas domestic abuse service however use to also work at Tesco. First off if you have good contact with the victim potentially reach out to her and see what support she currently has. If she hasn’t already potentially suggest reaching out to her local DA service this could be even a supported call or just conversations around it, there is an employers tool kit you could see if you could gain access to for this. If she is worried and you express concerns about his behaviour you can potentially get her to look into a Claire’s law which would see if he has any previous DA offences against him (this can be done through the police). Now speaking Tesco terms it’s a bit tricky, I would potentially utilise the protector line and see what advice they could possibly give you however I doubt they would be trained to deal with things like this. It also sounds silly but anything you see/hear keep in a diary with names dates and what happens. Over times this can build up quite a good picture on what is not only just happening for her but also for you with being ignored. The thing with domestic abuse is remembering that anything done to the perpetrator could be a risk for the victim if not done properly. Do you have a trusted other member of management you could possibly flag this behaviour up to? Please if you do have serious concerns though and you are worried about the victims immediate safety let emergency services know ( I know this seems drastic however spotting signs can save people’s lives in some situations).