Immaturity can be annoying and it surely does not help relationships. See Signs of immaturity in a relationship:
1. Always wanting things your way: When you both refuse to compromise, it is a very clear sign. It is best to know that you will never have things your way all the time.
2. Not relenting during an argument: Another common sign is not giving up during an argument and always trying to have the last say.
3. Jealousy over everything: Even if jealousy is normal, it should not be tolerated all the time. The more you allow it, the more it destroys your relationship.