u/Beaivimon

There's a tremendous difference in choosing to or to not use a comma in a situation that can be argued as either a dependent or independent clause and using their/there/they're wrong, etc.

Let's provide an example for both scenarios using a random Digimon Adventure headcanon scene:

1. Hikari and Miyako had a tough choice to make and they had to understand the stakes at hand.
2. Hikari realized that they're about to enter a realm of unknown and danger.

The first sentence can be argued as either a dependent or independent clause because while it looks like the "stakes at hand" portion depends on the "tough choice" part, you can also argue that the last clause can be a separate sentence. Neither is incorrect. The second sentence clearly requires you to use they're as in short for they are. Using their and there makes zero sense.

No one is perfect when it comes to grammar. I make a ton of mistakes, but the mistakes I make all happen to be the former not the latter. English isn't my native language either. Please, please, please be extra diligent when it comes to not making grammar mistakes on the second example.