I have never paid credit card interest, never bought a toy with a loan and would never advocate getting in debt to YOLO, but you also can't put off enjoying life while you build your place in it. 5 years easily becomes 10, becomes 20, and if it's not enjoyable, resentment can really mess with a relationship. The key is finding the balance. And there are always ways to do things without breaking the bank. I skiied for free for 25 years by volunteering, first as ski patrol, then as race crew.
If you're with a good woman (& it sounds like the OP is), you'll support her with the things that are important to her and she'll do the same for you. Sure, the mortgage may take a little longer to pay off or the car may not be as fancy, but if you're enjoying yourself along the way, those things become less important.
My comment about price of the ring was really a push to say, if you're gonna do something, do it right. If both of you aren't into the rings, or don't like the diamond industry, that's great. But if you want to surprise her with something special, do it when you realistically can, and make it nice. Although we're technically not married, I've been with my spouse for 24 great years. Neither of us felt the need for the ring or piece of paper. For our 20th anniversary, I wanted to do something special, so I pre-selected 5 designs & surprised her with a stop at the shop. It may have taken a while before I could do it, but it was worth every penny to do it right.