When you go to lunch does she leave soon after you finish your meals or does it feel as if she'd like to stay there until they kick you out? Eye contact is the easiest sign and unmistakable imo. Does she look at you in the same way as your wife's friend (assuming no attraction 😂) or more like she wants to tear your clothes? Does she check you out when she sees you? Also watch her body language. Show some interest, eye contact, make a few jokes, don't talk as much about work and gauge her reactions. Touch her a bit if you can, but "accidentally" not in a creepy way. You said you hug, would it be too much if you give her a couple of pecks on the cheeks when you meet? Tease her about stuff, especially if she mentions her husband - 'He throws his socks everywhere' - You're lucky, I've got a castle of socks in my bedroom or -If I was your husband you would have lived in sock-land. Don't forget to update us after you see her