There is a rather simple rule: If your happiness is mostly burdened by difficulties within the relationship, then come together! This is often a faster and more powerfull way to improve your situation.
If your partner is not interested to join, try to motivate him or her for one session. If he or she refuses also this, just come alone and we will see, how to invite your parter or if it is even more helpful at the beginning, to come alone.
If you want to clarify topics that your partner has been bored with for a long time, you do not have to bring your beloved one with you. Also in cases of violence, abuse or (co-)addiction it can be best, to come first alone.
Whenever it could be helpful, to change the setting, I will suggest this. But it is you, who keeps the control and decides, what next step you want to try.