Human nature being what it is – she might just be willing to listen if the guy’s just a chump who needed a wake up call and is now willing to make significant visible changes to win her back. Key word significant (maybe I’d go so far as to say dramatic).
It isn’t without risk for her (or him) to consider this – the world’s full of unhappy marriages where someone made a big leap into a commitment with someone out of coercion, pity, ultimatum. So even if he shows up with a ring and asks if you guys can get married in three months, and runs out to tell his whole family that’s the plan, think it over.
What isn’t open to question is that if his “counter-offer” is the least possible concession that might win you back (i.e., the stuff you’ve heard before – “I’ll try to work on the intimacy/commitment issues, I’m looking into therapy, I’ve been talking to a clergyman to work through these issues, if you get back together we can think about getting engaged sometime soon”) – don’t buy it. Guys who are into making a relationship permanent and serious have a timetable, know the (pretty damn simple) steps they need to take to show their commitment and advance the ball. People vary in the speed with which they proceed to commitment, but the odds IME indicate that after a few years, an offer to take the smallest incremental step that will avert confrontation/breakup is the classic male game of conflict avoidance, kicking the can down the road, buying time, stalling, hoping something will magically change to make him crazy about a girl he’s – eh – about now.
I don’t demonize guys for doing this, there’s obviously something hardwired (if you can’t tell, I’m speaking from experience with friends, and myself, whom I’ve seen do this, even fooling themselves/ourselves that it’s kinder than a breakup) in some men that sets up this fundamental discord between (some) men and (some) women after a few years of dating. Doesn’t mean he’s a jerk or you’re a nag/clingy, just means you both have to look out for your own interests and do what’s best for both of you in the long run.