Perhaps its just my experience but ive met a couple of ex-marines in the past and they were very arrogant not very nice people. I dont know whether thats because thats just the kind of people they always were or due to their experiences, training or things they had done and seen, but based on that no I wouldnt. Like I said thats a generaliseation based on 2 people though and of course it depends on the individual.
Ultimatly however the likelyhood is that id not be comfortable or happy dating someone with that mentality or the ability to get into the frame of mind as to where they could kill someone for their job. Id also not be happy knowing they were going off into a warzone, I couldnt build a life with someone- kids for example knowing they were putting themselves into that situation.