Communication is the key to any relationship. With bad communication, problems crop up at unexpected places. This is a classical case. Sometimes, we say things we don’t mean without even realizing it. We continue to go about our day, unaware of the fact that we hurt someone's feelings. It is important to let someone know when they hurt your feelings with their words. They will learn your sensitivities, and be able to explain what they actually meant.
What you say can make a big difference to your relationship. How will the listener know what you mean? The listener only picks up your words and makes interpretations. Choosing the right words while communicating is important. If you know about your partner's sensitivities about a subject, you have to be very careful while talking even in jest. Your tone has to be perfect and you have to be careful while speaking. You never know when you will hurt your partner's feelings. This communication care is very important in keeping a healthy relationship.
Freedom in communication can be taken if you are sure that your partner understands you well and will not take any talk otherwise. In that case, you both behave like close friends, who speak their mind without bothering. If the relationship has not reached that level you have to be careful while talking. Loose talk can spoil a relationship.
It is also smart to not communicate about important subjects over text. Tone and meaning can get lost and misinterpreted. Speaking in person opens the door for more intimacy and the truth.