Are relationships supposed to be stressful?

In general, stress is a part of life.  There is both good and bad stress, which will exist in any relationship you have with someone.  Stress that we would identify as “positive or “good” is the type of stress we associate with positive change.  For example, if you are offered a new job opportunity, there may be stress associated with learning new skills with the new job, but the outcome will be positive as your skills will be enhanced.  A negative or “bad” type of stress causes more harm; for example, if you are working out and use too much weight, you would be putting strain on your body that is causing damage to your muscles. 

When it comes to relationships, absolutely, there will be all different types of situations that cause stress.  Sometimes these types of stresses can be positive and negative, sometimes both almost simultaneously.  Being in a relationship with someone can be new and exciting initially, but it can also be anxiety-provoking because you are still getting to know that person.  Perhaps they say or do certain things you are not accustomed to and do not like; this could be negative stress dependent on the extent to which it is bothersome for you.  But perhaps this partner also encourages you to engage in activities or challenge unhealthy thought patterns you struggle with and, although stress, can have a positive outcome.  For example, if you are more socially isolated and this person encourages you to go out and try new things, this could be stressful to do, but in the long run, it will help to enhance your social skills. 

As the relationship progresses, perhaps you experience more negative stress, such as having disagreements that lead to raised voices or hurtful things being said or done to one another.  Although not necessarily something pleasant to encounter, it is still a common occurrence in relationships.  However, with the support of healthy communication skills and good boundary setting, the frequency and intensity of these types of negative experiences should theoretically reduce over time.  If there is no reduction, and perhaps this type of negative stress worsens, it may be a good idea to seek professional/counseling help to work through these stressors.