Is it normal that I don't know how to polietly end a conversation?

This has happened to me every now and then but it's definitely more awkward for me to do it offline, for some reason. I think it's because when doing something like e-mail you are given extra time to think of closers and think over your words, you can't really do that in a public setting.

I almost always end up saying something I regret because I often feel like I'm being rushed to answer a question. If you aren't comfortable with the person it can further make things awkward. I know I have had many awkward conversations when trying to contemplate not only how to progress the conversation but bring it to a end too. (All this being for offline situations.)

The things you mentioned as closers don't sound that bad. As long as they can get the job done without coming off as being rude, that's good. Heck! You shouldn't even have to tell them why you are going. However, some people won't take a simple goodbye for an answer. In that case you'll either have to ignore them or lay the law down!

As for people sending 50+ texts. Tell them exactly how you feel. Don't mince your words to appease them. Be straightforward and honest.