Does anyone feel scared watching intimate scenes?

I just came back from watching Titanic 3D, and this happens in almost every movie/tv programme by the way, it's like when I was watching the scene with rose and jack in the old fashioned car, and then they give each other that look and I don't need to say what happens next ... anyway half of me is like "Awwwww that's sooooo romantic" and imagining myself being in love and half of me is almost afraid, like my heart pounds, because intimate scenes show vulnerability. Like how do you know that they're not just going to use you for sex and then ignore you the next minute? how do you know you're gonna end up happy ever after? I'm just scared of getting hurt. Because over half the people who get married end up divorced, I know a lot of couples who got divorced or people who break up. People cheat on each other, fall apart by anyother means, It sucks! How do you know who to trust? And I'm scared I might never find that true love and be happily married. If I had a crystal ball and I knew I was going to be happy forever with the man i love and we were going to be married with children and grandchildren than I wouldn't have a problem! I guess I'm just afraid of the unknown. So because of my fear, is it normal to feel scared watching these scenes? (also, I know people who were sexually abused, not me though but I know people who were) I want to fall madly in love and be happy ever after but I'm scared I can't control whether that will happen or not. Do I just worry about things too much? Do I need a councellor or something? Or am I flatout childish in that no one else knows either but doesn't carry on like this...