I'll look after him, of course, but I do think it's something the two of you should speak about.

[she hesitates. she doesn't want to moralize or lecture, nor does she want to make him worry, but she does think this is important to say.]

I'm certain you've realized it, but you're very lucky to have him here. If he were to leave and anything were left unspoken, or a problem unresolved...