Dear Mary: I always end up subsidising my greedy friend’s lunch

Q. I have lunch once a month with an old university friend. Over the years we have both thickened out but I now make a serious effort to curb my appetite. I will usually order one glass of white wine and a starter-sized mozzarella salad, but my friend invariably has the main course, the cheeseboard and three glasses of wine followed by a digestif. We’ve always split the bill but now that my ‘share’ is, for example, £20 to his £120, I have started to feel a tiny bit bitter about paying £70 — especially since I don’t think he has noticed the anomaly. After all this time, how can I suggest we divide the bill differently, without giving the impression that I have been harbouring a resentment? I love my friend and I know he’s not exploitative, it’s just that he doesn’t think about these things and hardly notices what I eat.