Relationships can be messy. And in a lot of relationships, there comes a moment when you realize things just aren't working out the way they should be.

Whether it's a significant behavior that triggers this thought or an insignificant moment, it can signal the end of a relationship is approaching.

I asked 20 college students what these moments were for them in their relationships and this is what they had to say:

1. "When I realized I still had feelings for my ex"

I was with my boyfriend one night and realized how much I missed my ex and how much I'd rather be with him. We still haven't broken up yet but I'm going to do it soon.

- Female, 20

2. "When he dressed up as Donald Trump for Halloween and yelled racial slurs and started arguments with people"

I broke up with him within hours.

- Female, 21

3. " When he started obsessing over a gift another girl got him for his birthday"

He ended it after about a week

- Female, 20 but 15 when this happened

4. I knew at the very beginning that I wasn't into him

He actually broke up with me three months into the relationship, which worked out well.

- Female, 21

5. "I could tell that our lives were going in different directions"

My high school boyfriend and I had been dating for two years by the time I had my senior prom. He was driving us to the dance downtown and somehow I looked over at him and knew we were going to break up. It'd been a good two years and we'd talked about marriage, but I could tell that our lives were going in different directions.

I didn't want to throw away such a good relationship too quickly and I hoped that our differences might not be completely relationship-ending, so I didn't break up right away. After some prayer, I suggested that we take a temporary break. He wanted us to decide then and there about breaking up, since taking a break often lead to that and he didn't want to drag it out. We talked for a while and broke up. It was hard on both of us.

- Female, 21

6. "This cutie pulled up next to me, honked, and gave me a compliment"

When I'm in a relationship, I am all about that person. I don't even look at another person. I was in my car, stopped at a red light, and this cutie pulled up next to me, honked, and then gave me a compliment. I gave him some cheesy compliment back like "I really like your eyes" or something. It was harmless flirting, but to me, that was my sign to get out of the relationship because I wasn't all wrapped up in my then-boyfriend anymore.

I broke up with him two days later.

- Female, 20

7. "When I learned that her parents were insulting me and she didn’t speak up in my defense"

It took me 2.5 years to break up with her, because of depression.

- Male, 37

8. "When we got into a fight and I was the one to apologize and he never did"

We broke up a week later.

- Female, 20

9. "We were just angry at each other all the time"

It was something that developed over time, but I didn’t realize it until I was sitting in the car fighting with him, and I didn’t remember what we were fighting about, but I kept fighting anyway. We were just angry with each other all the time.

It took a year and a half to end the relationship.

- Female, 20

10. "They forgot my birthday"

And didn't remember for three days. We broke up four months later.

- Female, 19

11. "He met another girl at college"

My boyfriend had gone out of state for college. He came back and was completely different. He was allowed to go out and meet new people, but he did not want me to do the same when I left for college. He also met another girl at college and would call/text her all the time when we were together. We were just holding on to strands of our relationship at that point. We broke up four months later.

- Female, 20

12. "He didn't even care about the fact that I was upset"

We were on the way home from seeing “The Purge 3” and the whole drive home I was bawling while he was explaining how the movie was so awful because it victimized the white man. He didn’t even care about the fact that I was upset. I had to scream at him to get him to understand that I just wanted to have a nice date. It was like in that snap moment I realized that he didn’t care about my feelings and that the relationship was completely one-sided. We didn't break up until eight months after that.

- Female, 20

13. "When he told me no one else would ever love me if I left him"

It lasted another month.

- 20, Female

14. "When I was in the hospital for a panic attack and he told me it was my fault for arguing with him "

He broke up with me that night.

- 20, Female

15. "I found out he had cheated on me"

I ended it that day.

- 20, Female

16. "When I kissed another guy"

We broke up the next day.

- 22, Female (16 when this happened)

17. "When he started having sex with me while I was asleep"

(This is rape, by the way, and is not okay under any circumstances unless both parties discussed and agreed to it in advance)

It took three months for us to break up.

- 21, Female

18. I knew it was over three weeks into college.

I broke up with him a week later.

- 18, Female

19. "I knew my relationship was over when everything that person did made me feel repulsed and annoyed"

It took about two months for me to end it.

- 18, Female

20. When my boyfriend told me he "wanted to talk."

It was over immediately.

- 19, Female