Just something to consider....
The subspecialties available to internal med grads are almost endless, which I find extremely fascinating (I am a married, female, 4th year student going into surgery - oh - and have a 2 year old). I am assuming his residency was pretty much hell. Depending on what kind of practice he goes into as an internist - his life could be just as bad as residency was. Unless your hubby decided to NOT do hospital work and only do office....well...I'm not sure you will see any change from residency to attending. However, if he's interested in one of the subspecialties that may provide him with a more family-friendly career.....that would certainly be worth the extra couple of years in my opinion. Just something to think about.
And, (Keep in mind, I know nothing about you, your husband, or your marraige)....your husband has worked hard to get where he is. Your entire family has sacrificed. It would be a shame that everyone has been a part of this long journey...and he didn't end up doing what he really wanted to do. Some fellowships are WAY more intense than residency - I've heard that interventional cardiology is one of those. However, I've also heard that some fellowships are pretty much bankers hours ...I heard hem/onc was like that. Now, I don't know if those things are true...but the situation will be dependent on what he wants to do.
When my husband and I discussed what I would be doing the rest of my life - he said those exact things to me - "you've worked too hard to not do what you want in the end".
Anyway - my point is this - it may mean more training for a couple of years with barely enough money to live on...but he either 1)has fallen in love with a career that he knows he could spend the rest of his life doing....or 2) he has his eye on a career that would enable him to spend more time with his family in the long run 3)both - which would make him a very lucky person.
Good luck.....and don't forget to simply communicate with him your ideas, fears, concerns. Also, simply ASK him why he's thinking of this....