A relationship that is unhealthy is often one that has progressed too fast. While moving fast can be exciting, it might also be a sign that the other person is rushing. If someone is pressuring you for more and more of your time, or insisting on a level of intimacy that you are not ready for, it can be a sign that the other person does not have your best interests at heart.
If the other person in the relationship constantly belittles your feelings and criticizes your ideas, you are suffering from verbal abuse. Verbal abuse can be difficult to diagnose, especially if the person you are dating frames it in a joking fashion or if they are subtle about how they are getting their point across. However, it is domineering behavior and it has the effect of making you afraid to disagree. If verbal abuse continues after you have asked for it to stop, the relationship is not a healthy one.
Many people who deeply invested in each other will spend many hours together, but if you notice that you are not spending time with anyone else, this is a warning sign. One aspect of many unhealthy dating relationships is that one person will try to isolate the other person from their friends and family. This behavior will lead to you becoming more and more dependent on the relationship, which can be problematic and even dangerous if the relationship turns abusive.
A person who is different from day to day and expects you to keep up is inconsistent, and this can be a sign that the dating relationship is not a healthy one. Someone who is inconsistent will leave you worn out and mistrustful. In some cases, it may be because the person is confused about himself, but in others, it can be a deliberate tactic used to control you or to keep you nervous.
One sign of a toxic, unhealthy relationship is an inability to accept responsibility. If you notice that the other person never owns up to anything that they have done, and if the fault always lies with other people, this is a sign that the relationship is not a good one. Someone who never takes responsibility for themselves is going to be unreliable, and sooner or later, you will find them blaming you.
If at any point you are afraid of the other person, it is time to get out. Fear is an emotion that we have to warn us of danger, so listen to your instincts. If you find yourself acting in a way that is contrary to your nature or if you find that you are not bringing things up because of concern about how the other person is going to react, think seriously about what that might mean.