Girls, this is so complicated!! I need help!!?

i feel as if this will ruin my life. I am going into the 8th grade. i had 2 girlfriends this year. the first moved. The second I broke up with. then when i asked out a girl that really liked but i was always to shy to ask out. when i did they said no. i asked why. she said, "because i don't want to be depressed in my future." At first i thought, "well Thanks!!" 3 days later i asked one of her friends what she meant by "the future." she said that she knew i wanted to be in the Marine Corps. I first thought, most likely we would not be in each others futures. Then i asked how she knew that. the friend said that everyone knew that. that all the girls in the 7th grade new that. Then 5 days later, in math, another girl wanted to know what i wanted to do in the future. She sounded like she already knew. I said a Marine. Then she said and quote, "I feel sorry for your wife." Then she looked away. please tell me why it is so frightening. Besides death which is less than a 50% outcome. please describe it. also what should i say to a girl to get past that? please describe.