Fiance wants to go to combat...

My fiance (soon to be husband in 2 months) is in the Marine Corps. We just past his 2 year mark in June 2018. He started out in Infantry as a machine gunner. He had his first deployment August 2017 to March 2018 to Japan/South Korea. While it was very hard with little communication and different time zones, he describes it as being easy and nothing different than being on base. He has expressed his frustration with feeling like he has no real responsibility, wants to be where the action is and wants to make a change. So he tried out for Sniper Scouts and got in. This has always been a goal of his and he feels he'll be better challenged. Another deployment is on the table - but not combat. He's recently been thinking about possibly transferring to the Army in the future at an attempt to get to a combat zone. I'm worried that his hunger for action will get him hurt or worse. I understand it's in his job description but it's the seeking out part I'm worried about. Also, he said if he does transfer to the Army, he wants to try for Special Forces. I need thoughts/advise on what to do/say