There are plenty of single parents who use their kids to get out of almost every obligation. Even obligations to themselves, for say... exercise, dating, taking responsibility for their own actions. And I have been the dad who apologized for checking his phone when a text dinged while on a date.
The goal is never to blame the other person for the breakup, even if they were the reason you are breaking up. Always take your responsibility for the miss. And make it about the chemistry, the mix, the overall relationship and not about them or their poor behavior. Remember, you are leaving the relationship, not trying to teach them a lesson or educate them.
I'm almost always hopeful and joyous about this new journey. As a single dad, I have more time and more complications than when I was married. And if we can find the balance of these three traits between us, perhaps we can build "what's next" together.