On average, the first years in the Marines can put a significant strain on relationships. That said, your age is far older than the average recruit & you state you are happily married, so your mileage may vary.
Just know that the training and deployment routines can create a lot of separation time. Modern communications, and more importantly your spouse's ability to cope, fend for herself, and bond with other spouses in similar straits can go a long way towards easing the situation.
Your desire to Serve is commendable, as is your choice of branch, but be sure your wife is as Gung Ho as you are.
As for the Marines itself, my own Boot Camp experiences are almost two decades ago. I was of a similar age, and that made the experience simultaneously tougher and easier. Tougher in that more was demanded of the the older recruits in terms of Leadership and Responsibility, and easier in that the rah-rah and chicken???? games were obvious for what they were.
Best advice I can give re the Boot Camp experience - Do everything you are charged to do as hard and fast and well as you are able, and expect to get dumped on regardless (either Individually or Collectively).
For the choice of MOS / Recruiter promises - you haven't said anything about your desired field or your particular abilities. Have you taken the ASVAB tests yet? Any Branch has recruitment goals to meet, though it is my understanding that isn't very difficult these days. Many MOSs are in high demand do to the current OpTempo, which means relaxed entry requirements AND longer / more frequent deployments.
You will get many promises from a recruiter. trust nothing. well, nothing but the contract you'll sign, which will state your primary MOS. The recruiter is supposed to pre-qualify you for this position, via said ASVAB tests, any educational background, etc. The service may not have a need for personnel in the filed you desire, in which case you'll likely not get it. Sometimes alternate MOSs can be selected, just be darned sure that they are in the same mega-field you desire - ie, don't accept Motor Transport if your primary choice is a Combat MOS.
More on separation - If you pursue combat arms, and particularly specialties key in the Fleet Marine Force (or whatever they are calling it these days), your deployments and separations, especially in the beginning, will be lengthy, with 6-9mos rotations at sea, or mmore likely right now, in a theater of war.
If you have more questions, or which to discuss the Marines at length, send me a private message, we'll exchange email addys.
Good luck with your military desires, and good health