When someone has been around someone for a period of time and they know that they will be leaving soon and might not ever see that person again. The person that is leaving doesn't necessarily tell them that they are leaving and that they enjoyed being around them and knowing them. But they act in a different way than they normally do towards that person the last time they are around them. Acting in a different manner to show that they enjoyed being around them.

What is a word that could describe that situation.