I've done it. I've sent pity flowers anonymously to a couple female friends who have been struggling with finding a man. BUT only when I was single OR if I already spent the same if not more on the GF and I had a little surplus cash to make someone else's day feel better. I don't see it as any different to buying a female friend drinks after work. I didn't tell my SO because I want to avoid conversations such as the one above and it's my money. There's zero attraction on my side so I didn't see the point.

My concern is that your husband felt guilty about it. If he lavished you with gifts first and had a little left over to buy that woman flowers, you can believe he did it out of a sense of altruism, and there shouldn't be anything to be guilty about. It really seems to me like he doesn't know how to cover his tracks. Because if I was married and knew that my wife had access to my credit card statement and wanted to have an affair, I'd be buying flowers and booking hotel rooms with CASH.