What should I do about her?

So this is relating to my relationship. I met this girl a year ago, and have been in a relationship for a year come January 1st. I love her with all my heart, and it took me a few months, or even the better part of the year to realize this. We rarely fight, and shes my best friend I can tell her anything and ALWAYS rely on her. There is just something about her whenever I see her. No, shes not the best looking but I realized that doesnt matter cause when I look at her and what she does, I love every part of her, there is just something about her I cant explain. Now comes the question. Come End of May I am traveling abroad to Europe and backpacking across multiple countries. Something I cant wait to do. I have plenty of friends across Europe all of which I plan of visiting, even past friends I have been involved with romantically. I told my GF that I plan on going for 2 months across Europe to travel, and she said exactly "I know you are going to break up" and like I said we love each other and know each other so well, so yes I want to. But aside from sparking old flames, traveling single is a different experience, idk how to explain it. But its more freedom you know, allows for more spontaniality. I dont want to have to check back with her ever day or week cause who knows if i wil even be by a phone. And I dont want her to worry if i miss a planned phone call even for a few weeks. Plus I dont want her waiting for me all summer, cause who knows she may meet someone else. Lastly, shes my first legit gf, im 20 years old so i know I wont marry her at least not now, but that doesnt mean I cant say I love her. I figure since it worked out so well now, than why couldnt it again in 3 months, a year or even 10 years. I am the type of person that wants and loves experience. The thing is this. How do i REALLY know I lovve her if I dont have anyone else to compare the feeling too? thats how I view this, if i really do love her and want to marry her than I have to make sure first. So that means experimenting with other girls, let it be a few weeks, months or years. YEs I know i could loose her, but it wouldn't be fair having her wait for me and me knowing I wont marry her. I have to much curiosity about others, now that im in the dating game. But everyday since I have made the decision to go to Europe I think about leaving her. Is it right to break up with her? Or say I wana take a break and see what happens when im back? is it right to do it when I leave next year in MAy and "drag" her on until than? or should I do it now before she gets more attached? I love her so much, thats what makes this so hard. I just dont know what to do. But how do I know that I REALLY do love her, cause I have nothing else to compare the feeling too...thanks for any advice guys. This is probably more of a airing my thoughts