my fiancé really wants to go into the military. help?!

Charisma • Love yourself ✌🏻️
My amazing, loving, dedicated fiancé really wants to join the military. But I am increasingly terrified! He was trying to go into the marines but he can't gain enough weight and he was making himself sick :( so now he doesn't know what to do! If anyone has any advise or help it would be very much appreciated thank you loves!