As has been stated, this is more of a relationship issue, but I will spout my 2 rubles.
Your question alone has many variables and 99% of them all revolve in how your relationship is with your family. I can/will share a few examples of myself and friends of mine.
-A friend of mine did his initial training. This lasted just over a year when you combine all the training and PAT time. As time went on, he grew more distant with his family and gave the standard "oh, same ol', same ol'" answer. This distancing also caused him to find comfort and solace in the company of his coursemates who were 10 years his junior. His wife noted to me that before the military he didn't go out 'drinking with the boys' and was generally a well rounded family man. She was also under stress due to the fact they had a brand new child (their first) who had been around his daddy for maybe 2mon in total of the first year of his life due to this training.
How I weighed in to her on this was that she needed to communicate with him her worries and concerns. Men are not mind readers and even less-so when only corrisponding over the telephone. She did this and they worked through a really tough part of their marriage - for the military person, it's how do I stay connected to my family when away and how do I stay a part of their lives while I'm gone? They both had to compromise and worked through the issue together. Since finishing his training, he is involved in his family affairs and a pretty darn good father and husband. What I can convey to you is that the initial training will likely be the biggest stress for your family aside from deployment. Your whole career will not be like it is in training.
-I met my wife and we were together for 3yrs before getting married. In that time, the longest I was away was 2-3wks at a time and that was maybe twice a year (if that). We were married and she became pregnant. As fate would have it, my job went crazy. Here is a breakdown of the last year:
2.5mon on course
2mon on exercise
2.5mon on another course
1mon teaching
1.5mon on exercise
0.5mon on extending training days where I would leave for 5am and back for 10pm
That's 10 of the last 13 months I have had minimal interaction with my family (weekends I had except for exercise tasks). I felt immensely guilty for not being there and had to ask my wife her feelings on it. She understood why I was gone but reassured me that although it may not be preferable, it would not last forever. As has been stated by mrjasonc, I have allowed her to do as she pleases in the house and run it the way that works for her. I still feel I matter in the relationship b/c we discuss any major purchases or changes. rmc_wannabe stated that the army won't weaken a strong marriage, nor strengthen a weak one. I am thankful the say I have the former for sure.
To be fair, I should put a negative point. However, I cannot do that. Yes, the military lifestyle can be a big stress on the family, but from my experience, it's not what breaks one if that's what you are concerned about. In the end, it all came down to how the marriage was. Yes, you likely have heard about a wife's infidelity while her husband is deployed or about kids growing up to be brats due to having no father figure due to the army, but those things happen in any job and in any walk of life. I used to date a very co-dependant person who I thankfully did not marry b/c she wouldn't have been able to handle the time apart. My question to you is how is your wife? Is she strong and independant? How are your kids? Take all that information and apply it to any job where you can be gone a lot or are in a dangerous profession; policeman, firefighter, Alaskan King Crab fisherman. I am very proud of my wife and all she has accomplished, essentially, by herself. She knows I love her and that we are a team. My kids are great. They support each other and are a little team unto themselves. They can readily adapt to changing situations and people (mind you, they both are young still). I, however, am not in a purple trade. I hear that the chance to be posted anywhere or across the country is higher (though, with fiscal restraints, that is much less often that I may be alluding to).
You will have to sit and talk to your wife. If you can, as a couple, talk to other couples who have either one or both halves in the military. Always remember that it's not the CAF that will make or break your marriage, it's the people in it. The CAF will just provide opportunities to test the foundation of your marriage.