If I'm going out with a girl, and I honestly don't love her, then I'd let her know that. Simple way to put it without her getting pissed is "I'm a fan of not leading people on, and you're no exception. To be honest with you, I'm not quite in love. Now don't get me wrong, you're an amazing girl, and I truly care about you, I just don't think it's love yet. At the moment, it's strong infatuation." Of course she might get pissed, but then again she might understand. I'm the kind of guy that never says "I love you" unless I feel I mean it, and I've only said it once.
On the other hand, if you want the sweet approach, do this. Figure out what attracts you to her. What little things does she do that you find cute or funny or whatever. Mention those. Don't just talk about her body. Do that at the end. Be like "Why? Well, because when you smile your eyes scrunch up and thats just incredibly cute, and I love the way you laugh. (Insert personalized BS here). Oh and by the way, you've got a killer ass" and then give a big ole sh*tty grin and wink.
