I want to cheat on my boyfriend of 2 years!

ja
Ok, no I don't want to cheat on my boyfriend but those thoughts go through my head as my only solution to my problem..
I have been dating my boyfriend for 2 years. I'm 19 and he's 20, about to be 21. I lost my virginity to him, but I wasn't his first. He had been with multiple girls before me and I didn't take that very well.
We just hit our 2 year relationship anniversary last week (11/23) and now more than ever I feel so tied down. I love my boyfriend so much. He is THE love of my life and I can't picture the rest of my life without him, but I keep thinking about the experiences I am missing out on with other guys.
Back in high school, I had a huge crush on this guy for like 4 years and it went nowhere besides me giving him a bj. I was so young (17) and didn't want to be used as an object by him (or used for sex) so I ended our thing we had going on. But now, I'm thinking about him again and how I wish I could've had sex with him. I know, I know, I'm not supposed to be feeling this way, but until you've been in someone's shoes, you should judge. This is when people cheat, and now I'm starting to see why people do it.. and no. I will NEVER cheat on my BF but now I can see why people do it..
I don't have many friends to talk about this with, but has anyone else experienced this? My boyfriend and I have talked about this, and even though he has been with other people, we both agree that we still want to experience other people. We are both so young but we know we want to be together forever. Has anyone taken a break to be with other people, and then got back with their so? If so, did it calm those thoughts of "missing out on experiences"? I am not here to be judged. I want advise.. tips,anything. Thanks!