If someone replies, "Goodbye!" you respond, "You too!" or simply, "Goodbye!" You can say, "See you soon!" depending on the situation. Or "Have a safe travel!" if they are going on a trip. Asking someone to stay longer or come over again helps keep the friendship strong. If you do not want them to leave yet, you can say, "I had fun playing with you. Play with me again sometime." or " I will see you tomorrow for sure." Sometimes we use words that don't necessarily mean what we think they mean. For example, when someone says they have to go, they might actually mean they have to leave. In this case, their comment means that they have to go somewhere else first before coming back. Similarly, if someone says they will call you later but they don't, they may be trying to avoid talking to you. This would also be an excuse to break off the friendship. When someone says they have to go, they usually mean that they have to go somewhere else first before coming back. However, if they say it quickly and seem distracted, maybe they need some time by themselves without being interrupted. In this case, they are probably calling someone else over so they can gossip with them.