No thanks. That is not a good deal.
You can’t propagate the human species with heroin
And yes it changes things - I didn't believe so myself, but it did, for the better. And that's without kids. Anytime I see non-married couple with their kids, its mostly the guy. Women often say they are OK with that but then tell their close friends how they wish they could be married. All I see is insecure person - and literally everybody I've ever met in that situation is insecure, you just have to look close enough.
But it became a bit of an art to marry well and of course its never 100%, but then what in life is. It can't be done for physical attraction alone. I would say that the SO needs to be a damn nice person to live with (for you at least) if you remove any physical attractiveness. There are tons of people who have naturally and genuinely good heart. Marry those, and only those. The chances for good marriage compared to average just jumped through the roof.
The second part is at least equally hard - be a good partner and father, consistently even if not truly permanently. Family takes priority about any pathetic career you consider so important and awesome. Any party, trips, plans, and so on. Don't lose yourself in marriage/parenthood and keep something that makes you feel alive, but be ready to postpone/downtune it. Chances now are even higher.
The last part is to be sure both sides are actually, truly, long term compatible. This takes time to find out. Similar personalities are much easier to work with compared to opposites. It can be speeded up by spending a lot of time together, tough and challenging time. Long active travels are great, if not possible a lot of small intense travel helps. Don't extinguish arguments (but don't provoke them), and watch how other side reacts. How both your reaction combine. How you both handle de-escalation. Ideal is to find passions that you truly share, the more the better. I for example wouldn't be able to live long term with a lady which doesn't share with me some mountain/adrenaline sports. Mine shares all of them but it took quite some time to find her.
Most couples these days, married or not, fail at least some time in at least 1 of those aspects. Over time, its source of wedge that cracks relationships that seem perfect in the beginning. But they are perfect only through the lens of emotions, which change over time. Cold, hard facts about persons changes much less often if ever.
Perhaps this is immature. I'm not totally averse to responsibility. I have a career and a mortgage, and getting fired or going into default would be very bad. But it would be bad in a way that I'd recover from. An acrimonious divorce with an alimony award would really seem to make the rest of my life not worth living. Even a 5% chance of that is crazy.
Long story short, don't get married in Canada. Dave Foley on the Joe Rogan Podcasts (in like the 0-200's episodes) went through his divorce and explained how absurd it was.
Yes your ex can argue that you could make more but he could take a similar job with the same skill set that is less stressful. Or if he moves, less by cost of living adjustments etc...
But he should be able to quit, there's no forced employment. Obviously, the employer is not a party to the contract either that they have to keep him employed. So he would have to file a motion to decrease the alimony support unless things have been locked in by a separate joint agreement: MN calls this a Karon waiver. If the job is too stressful and impacting his mental health then he should present that evidence with justification from medical experts to the judge... That process could be stressful no doubt but should be worth it.
Alimony is also not always criminally enforceable like child support is. A judge could hold you in contempt but it's not going to do much to get you to work if there's no motivation to work. Then the judge would have the additional problem of you being in jail and not being able to work or having to explain to your employer or a new employer why you were in jail.
The courts really want a win:win here.