What is the most probable relationship between Lily and Charles?

W: Charles, I’m going to leave for the airport in half an hour.  Can I have a word with you first?
M: Yes, sure.  How long are you going to spend in Italy, by the way?
W: Oh, Just a week.  I’m going to see some new designers this time, so it will be quite interesting.  Now, you’ll remember to check the money every evening, won’t you?
M: Yes, I will.  Don’t worry.
W: And you won’t forget to lock all the doors when you leave?
M: No, I won’t.  Relax, Lily.
W: OK.  Well, I must get ready.  Oh, look at the weather.  It’s going to rain again.
M: What’s the weather like in Italy at this time of the year?
W: They say it’s quite warm and study.
M: Lucky you !
W: Charles, don’t forget I’m not going to have a holiday.  I’m going there to work! Now, I think I ought to call a taxi.