Can ADHD make my husband go back and forth on major life decisions?

I, like many others here, am new to this site. I've been married for less than a year, but prior to getting married, my husband and I broke up shortly a few years back due to him being overwhelmed with stress (finances, family, our relationship, school, work, etc.) but he quickly realized his mistake and asked me to take him back a short time later, and within a few months, we were engaged. He does a lot of things on impulse and without consideration for how they will affect me or make me feel, but I've never thought he did anything intentionally to hurt me, he just didn't think about things. About a month ago he came to me and said he thought that maybe he wasn't ready to be married, which escalated over the course of the next few weeks into him telling me he thought we should separate. In this short time period, he started seeing a counselor who has diagnosed him with ADHD. He's not on any medications just yet, but is seeing someone once a week and says he's committed to seeing him at least once a week for the next few months. Now he's saying he wants us to work things out (we were seeing a counselor together before all of this, because some of his impulsive actions and spending habits were causing a few problems in our otherwise happy marriage), he wants to commit to making change and becoming a better and more balanced person (to say he is obsessed with his work is an understatement). My question and my hesitation in taking him back is that I don't want a life of back and forth with him, always wondering if he's going to wake up one day and want something else. I know he can't promise me and no one else can, for that matter, that that won't happen, but I'm wondering if ADHD (I really don't know much about it, he was just diagnosed earlier this week, but I'd wondered for a while if he suffered from Bipolar Disorder...) can cause impulses so that someone would go back and forth on what they want out of their life and their marriage...impulsive behavior and acting before thinking is one thing...but telling your spouse you want out, you want in, you want out, you don't know...that's another story. Does anyone have thoughts on this yo-yo decision making?? I don't want to try to reconcile with him only to have it happen again in another few months or years when we have kids to consider. He's hurt me very deeply but I still love him and have hopes that things could work out if he stays committed to his counseling and to making those changes he said he needs and wants to make.