First of all, it think that maintaining your health is really important. Sexual attractiveness is important too.. because you cant help not being attracted to a scruffy beard and to hug a beer belly instead of your man.
I understand what you are saying. My husband is in the Army and he has actually been the one to push me to more healthy. We slack once in a while, and gain weight from time to time. But nothing drastic, we are comfortable enough with eachother to say .."hey choncho! ease up on the 3rd helping of cake!" haha its kind of funny, but we keep eachother in check, because it is important for him to look sexy for me, and for me to look sexy for him
and its important to stay healthy physically and emotionally. find out if hes depressed, beging comforatble is okay, but show him that you are inspired by working out, and that you want a workout partner. It might give you two some time to be together and sweat a litte! have a little competativeness

i think thats healthy! haha and keeps things fun and interesting.
Good luck with everything, please post and let us know how things are going!
izzy