If you are not willing to visit a therapist, at least for the moment, in order to get your relationship back on track, here are some ways you may try to do it yourself. But beware, since each relationship is unique, this doesn’t mean that one solution that worked on the other it will also work for you.
First, you must unilaterally disarm, make everything transparent between you and your partner and try to be as honest as possible. Then, it’s highly important to make a short analysis over your past and try to observe certain patterns that lead to weaker relationship.
Finally, always try to communicate what you feel and make sure you understand each other very well. If these things are difficult to manage, then it’s time to indeed visit a therapist.