Relapse seems a bit negative to me as if one must relapse or relapse is inherently bad. Relapse is normal and part of learning and healing. Unless you are planning to be completely abstinent for your entire life you will relapse. If we all relapse, then it doesn't seem to be relapse at all because we are moving forward, not backward which is implied by relapse. Since it is more like succumbing to urge, we could call it succumbing or yielding. However, both of those also imply that the urge is stronger than will power. One could try defer which implies a more voluntary choice. However, in actual use, such as I defer to your expertise, the implication is that the expert knows more. We don't want to empower the brain against us.
So what can we call it other than relapse?