I did this when I was about 23. I was with someone for 4 years and a bit. She always put other people first, was beautiful, and we had a great life together. That said, I knew I wanted to backpack Europe, meet other women, and ultimately learn who I was without someone else (independent me) and she wanted further commitment. I didn't want to meet girls just to fuck, I was interested in learning about who they were, where they came from, hobbies, goals in life, etc. The excitement of possibly dating someone new and the new lifestyle together was thrilling. I knew if I didn't do this I would live with the temptation (what if's) and maybe give in one day while still committed. I'm now in my thirties and getting married and I can say I won't have those temptations anymore. I've slept with randoms via one night stands, seeing girls for a couple weeks, threesomes, foursomes, fivesomes, swingers, vegas call girls, other backpackers... Now if ever the temptation arises, I have been there and know what I have now is better than any temporary fulfillment I experienced in my 20's.

I will note, she did move on and found someone she could start a life with, get married, have kids, etc in her mid to late twenties. So although it hurts at the time, long term it works out for both. And for me, it really let me see what else is out there so I could build a profile / priorities of what I would like in a SO. Being on the same page financially, humble, non-materialistic, family values, ect all outweighed appearance in a SO.

Big rant, but great question. Good luck to all.