I agree with PP, if you don’t like it, then you need to say something. Saying “I Love You” to the opposite sex, other than family and spouse, is definitely a red flag. Hate to be the bearer of bad news, but sounds like something is going on, or could go on…trust me. :o
If you, the wife, is uncomfortable with it, then yes it is inappropriate. Especially if your husband knows you don’t like it. He needs to ask this woman to stop.
That said, my best friend is a man. We’ve been friends for 20 years. We live hundreds of miles apart and call eachother occasionally. We always end our calls with an “I love you”. However, it’s not a romantic love. If his wife or my husband were uncomfortable with it, we wouldn’t say it anymore.