I'm divorced because I married at a young age, having few good dating experiences, because I didn't examine how compatible we might be (and found later that we wanted much different things out of life and neither of us were willing to budge), because I was not tolerant, and because we had absolutely nothing in common. In hindsight, not marrying in the temple was a red flag, the fact that we both disliked each other's families as well as those families not really appreciating our choice of spouse played a part, our completely different backgrounds, and lack of communication were huge. Intimacy was a huge problem but I didn't think to discuss it beforehand (would always recommend that btw), religious differences were as well- but as we were both LDS I didn't explore his real beliefs before marriage either. I assumed a lot.
I'm remarried to the love of my life forever because we both took the time to study each other's lives and families before we decided that was what we wanted, because we were best friends (we still stay up till all hours of the night talking- just like I used to w/ my gf's at slumber parties but better), and because we talked about absolutely everything, prayed about it, obtained consent from both our families, and married in the temple. Seriously, we talked about everything. Expectations about behavior, gospel principles, intimacy, children and parenting, homeschool vs. public school, vaccinating vs. not, politics, video games, family situations, what kinds of music we listen to (because there are many kinds I can't handle in the house) what would you do ifs...and much more, because I was worried after that first marriage and didn't want a repeat. I wanted to make sure we were absolutely clear on each others' positions and that after all that we still wanted to be married. I didn't know marriage could be so wonderful! He's perfect for me, and I try my best to make him happy :).