Ok. I think I get your situation.
If you are that invested in this guy that you'd worry what would happen if you discovered your more spiritual self, it may be time to think about the M word. Especially when there's a huge, free financial benefit to it. (he gets your pension benefits when you die.)
You may have other heirs. You can protect them with a prenup, a will, and a good lawyer.
Your decision to marry or not isn't our business, but the one financial reason to say no to marriage is that this guy may be a flake or a spendthrift. In which case, $78/month is money well spent to stay not married. $78/month may be money well spent to stay not married for non-financial reasons, too.
If you called up several different companies and this was the best price you got on a term life policy, this may be the best price out there.
I would not cancel LTC insurance.