They've been hurt before, and so they've forgotten how to trust others.
他们之前受过伤，所以忘记了如何信任别人。

"I'm really not good in relationships. It wasn't always that way. It's just that the first two women I was with cheated on me with a friend (different friend), both of whom told me about it later. I guess I developed a mindset that if I couldn't trust women and they were likely to do it again in the future, I might as well not deprive myself."
"我真的很不擅长谈恋爱。但世事无绝对。只是我的初恋和第二个对象都出轨了我的朋友（不同的朋友），她们都在出轨之后告诉了我这件事。我想，也许我因此有了这样的心态：如果我无法信任她，而她也有日后出轨的可能，那不如我自己先出轨好了。"

They weren't spending enough time with their S.O.
他们没有花足够的时间陪另一半

"Long-distance relationship. I was not the most caring or appreciative partner. Went out with friends. Very sexually aggressive girl came onto me. Went home with her. Felt awful afterwards. Confessed to everything even though I easily could have avoided being caught. Tried to salvage the relationship but it just didn't work."
"异地恋。我并不是那种会关心人、善解人意的伴侣。我经常与朋友出去嗨。身边也不乏主动性感的美女。于是我带她回家，但事后却十分后悔。尽管我知道这件事被知晓的可能性很低，但我还是坦白了。我试图挽救过我们的恋情，但却未能成功。"

They lost interest.
他们没了兴趣。

"I got bored. I cheated on him constantly. Always did a good job of hiding my dirty work. He never found out until I stopped hiding it. There was nothing really wrong with the relationship either. He treated me beautifully, sex was great, I just fell out of love, lost the attraction."
"我厌倦了。我总是给他戴绿帽子，掩饰的也很好。他从来都不知道我出轨，直到我不再瞒着他。这段感情其实并没有什么问题。他对我很好，我们的性生活也很融洽。我只是不爱了，他对我没有吸引力了。"

They were never in love to begin with.
他们从未相爱过。

"I was in a relationship where he loved me more than I loved him. I think I was just in it because it was habitual, comforting, and most of all, easy. I barely had to put in any work because whenever I needed him, he'll be there. It wasn't fair to him at all, but I honestly was just too comfortable and lazy to break up with him. Then I met someone. He made me laugh, he challenged me, and we had so many more things in common."
"那段恋情，他爱我比我爱他多得多。我想我愿意和他在一起可能是因为养成了习惯，和他在一起很舒服、很轻松吧。我几乎不需要付出任何精力，因为只要我需要他，他就会来到我身边。这对他一点也不公平，但说实话，和他在一起真的很舒适，舒适到我已经懒得和他分手了。之后，我遇到了另一个他。他会逗我笑、也会质疑我，我们的共同点真的很多。"

They felt neglected.
他们感觉被忽略了。

"The affection she showed me gradually slowed to a trickle and then just . . . nothing. No matter how hard I tried, she would just start treating me less like a partner and more like an obligation. It got to the point where she'd reject me for sex constantly. I felt unloved, unappreciated, and just flat-out shit."
"她对我的喜欢慢慢减少，甚至到最后不再喜欢了。无论我有多努力，她都不再像以前那样对我了，更像是在尽义务。当她总是拒绝和我啪啪啪的时候，我知道那一刻终于到来了。我感觉到她不爱我了、不欣赏我了，对我的感情归于平淡了。"