Student loan debt is very common. Pretty much every single person who's gone to college that didn't have rich parents to pay their way is going to come out in debt. Obviously you have established that he has to pay his share of living expenses and you don't want to be responsible for his debt. But I think you should also try to be more encouraging about getting him to pay more. Drowning in debt can make people feel helpless like there's nothing they can do to get out. It may not be that he isn't willing to make the effort but that he's exasperated on what he could do about the situation. You can suggest he try contacting his lender to get on income sensitive payments which are based on his current income. Does he like his current job even though it doesn't pay well enough? Does he have any prospects for advancement in his current company? If so, he may be staying because of that and not because he's too lazy/lacking motivation to apply for anything else. The economy is tough right not and a lot of people are trying to hold onto what jobs they do have. Do you have any other evidence that he's irresponsible with money besides him being unable to pay for his loans? Meaning, does he randomly splurge on Xbox games when he can't pay his share of the rent? Does he spend his whole paycheck in a weekend? If the answer is no, you're probably being unreasonable by saying he's "fiscally irresponsible."
Be aware that if you do get married, your debts merge so even if you don't want to be responsible you will end up in some way. It can affect you, but if you honestly want to wait for him to pay them off before getting married, you're going to have to wait until he's in his 40's because if it's as high as you say it will take 20 years to repay. Marriage is about being united in all fronts so if you're serious about him you have to find a way to work this out. FYI, I'm in the drowning in massive student loans debt boat myself, but my boyfriend who has no debt and makes more money than me has offered to pay more of the living expenses while I work towards paying down my debt.
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As someone with a lot of student debt, I can assure you most loan places will work with you to work out a payment plan that works with your income. So while you may not see a way out, your boyfriend is right, you need to let him handle it and give him time. Also, I can see why he would be reluctant to find a new job. It is a tough economy out there and it is hard to find a job, much less a good well-paying job. I think you need to sit back and let go of this. You two are still dating and he knows how you feel. So you need to give him some time to figure things out.
You say his fiscally irresponsible, but is he doing other things like going into debt for furniture or video games? Is he racking up credit card debt or is it just his student loans? If it is just the student loans, I don't think he is being fiscally irresponsible, but if it is that and other things then you might have a cause to worry. But in the end, he is a grown man and he has to deal with this on his own, you can't force him to do anything. You need to let go of your need to control and let him live and face the consequences of his choices himself. And if you can't do that, then maybe it is time to move on.
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