Believe it or not, lifestyle can have a huge affect on what makes a good engagement ring choice (or what makes a bad one). Things like her job, her hobbies, and how 'hard' she is 'on things' all matter -- and different rings can be better or poorer choices depending on her lifestyle. Similarly, rings all have maintenance over time, but some are more high maintenance than others. Her lifestyle might match certain styles better than others for this reason.
Consider Her Job
Certain occupations make wearing a ring a bit more of a hassle than others -- and the most problematic often require wearing gloves. A nurse or doctor, for example, is constantly putting on and taking off gloves. A ring that has a ton of bling and a massive amount of teeny tiny prong set stones might create more problems than a ring that is smoother or has less stones simply because prongs have a tendency to get caught on things. Additionally, prongs will wear down more quickly as they are constantly rubbed against by gloves (or various other types of hand work or activities), creating more regular maintenance. A third characteristic that can create problems is the height (or stone size). Rings that sit higher off the finger can pose problems by getting caught on things. Larger stones, of course, must sit higher to accommodate the culet of the stone. For certain occupations, it's imperative that you think about how tall a ring might be, how any stone(s) are set, and how smooth a design may be.
Other things to consider when thinking about occupation might be the number or size of the open space(s) in a design. An ornate, antique style with lots of teeny tiny holes, for example, might not be the best idea for a professional baker, ceramicist, or painter unless they're fine cleaning it constantly. Similarly, a dainty band or ring encrusted with diamonds might not be suited to a physical therapist, personal trainer, or professional athlete -- as these occupations tend to be harder on rings physically, with lots of activities resulting in damage or extreme wear. Some occupations may demand more durable widths, settings, or both.
Someone who comes in contact with chemicals on a daily basis or works with their hands, such as a gardener, hair dresser or massage therapist, may have their own unique set of considerations when it comes to the perfect forever ring. A gardening lifestyle may demand a harder, more durable stone for example. A massage therapist may require a low profile ring that won't be sharp or uncomfortable. A hairdresser might find herself wishing a diamond-encrusted ring didn't get caught in her clients' hair all the time.
On the flip side, many occupations will not conflict with even the daintiest of ring designs. For example -- if she spends most of her days typing away at a computer or traveling around on sales calls -- it's pretty safe to assume that her job won't be all that hard on her hands or her new ring.
Consider Her Hobbies
Although there are definite times one should not wear an engagement ring, we know that it's easier said than done, and every once in a while she's going to wear the ring when she shouldn't. For this reason, it's worth considering her hobbies and how likely she will be to abide by the rules of when not to wear her ring. For example -- if she's into crossfit and is committed to her daily after work ritual of going to the gym -- she may need a more durable, less dainty, or less diamond-encrusted ring.
Or... as a totally viable alternative, she may need a dedicated place to commit to putting her ring when she takes it off if she's got her heart set on a ring that doesn't exactly match her tough-on-things lifestyle. Lots of women opt to wear a rubber band as a placekeeper when they're doing something that might damage their 'real' ring.
On the opposite end of the spectrum -- wide (and yes, more durable) bands may pose another issue to consider for those with active lifestyles: swelling. We all naturally swell when we exert ourselves physically, and also tend to swell or shrink with the temperature or seasonally. If she's got her heart set on a very wide band (we're thinking modern styles here -- or anything over about 4mm), she'll need to know that the ring will fit more snugly during phsyical activity. She may find herself having to remove it before her daily yoga practice to avoid it becoming stuck or uncomfortable.
If her hobbies, on the other hand, are more aligned with wine tasting and broadway shows -- these considerations may be less important, and you may proceed toward the blingiest, most ornate ring-of-her-dreams you can find.
Consider Ring Styles
Some ring styles automatically lend themselves to certain high or low maintenance lifestyles, while others are solid, go-to designs that are somewhere in between. Typically, lower profile stones, bezel settings, and solitaire rings are all great options for those with active lifestyles or those who tend to be harder on things. Dainty filigree designs, shared prong or micropave halo designs, tall heads, teeny band widths, eternity styles, and multiple prong settings all tend to land themeslves in the 'high maintenance' category and aren't always well suited to an active lifestyle or occupation requiring lots of hand work, hand washing, or glove-wearing.
Consider Metal Choice
In addition, metal choice can play a role in durability and ease of wearability as well. When it comes to gold, Karat is usually more important than color when it comes to durability and strength -- with 14K being an industry standard, as it is a bit more hard and durable than 18k or 22k. Rose gold, however, is an exception to this rule.
While 14k white gold is the most durable, toughest choice among gold options, 14k yellow gold is a fine choice as well. Often rings will be made with both, traditionally using white gold for heads (or metal surrounding diamonds) and yellow gold for the shank or band (metal that wraps around the finger). Rose gold, however, is quite soft because of the metals it is alloyed with.
Rose gold should be used with caution. If not using rose gold is a deal breaker, though, you'll need to strongly consider both her lifestyle and all of the other design choices. A rose gold engagement ring may need to be thicker in some areas to provide more strength than might be necessary in another metal. It might also be wise to change certain design aspects to provide more strength, like opting not to have diamonds on the shank or going all the way around the shank or adding in additional supports underneath a halo style head. A good jeweler will be able to make the correct suggestions and modifications if you decide to go with rose gold.
Platinum is a unique metal that is often misunderstood. It is beautifully white, durable, and is known for its ability to last -- never wearing away but displacing instead. Despite it's longevity and strength, it's surface is actually quite soft, and some alloys can be very malleable, bending more easily than the same widths or thicknesses in gold. Because of these characteristics, platinum shows scratches and will lose it's high polish a bit quicker than gold -- and thin areas may risk bending if they are given the opportunity, or if the wearer is particularly hard on the ring.