Just the same as when you choose what you want to study: you have to like it so that you will enjoy every bit of it. Same thing for your job... I'm glad I joined Asia Against AIDS, because I don't really feel like I'm working, I enjoy it as if its part of my life.
When you love someone, will you let anything bad happen to them? I don't think so... and that's why having safe sex is important in your relationship -not only to prevent you from unwanted pregnancy but also from any STD's. Love wholeheartedly and keep it safe!