Today we talk about expressions related to a very powerful emotion: love.

More specifically, we talk about expressions related to love gone … not quite right: Relationships that do not work out, relationships that are more trouble than they are worth, and relationships that make you wish you were alone.

After all, while some happy couples are celebrating Valentine’s Day this month, plenty of other people have more complicated relationships. This show is for them.

Our first expression may sound impossible. It is the love-hate relationship.

“Love” and “hate” are opposites, but they are both strong emotions. In the case of a love-hate relationship, a couple just keeps going back and forth between the two feelings. One day they fight like cats and dogs. Another day they sing together like lovebirds.

You can also have a love-hate relationship with something besides another person. If you love some parts about your work, but hate other parts of it, you can say you have a love-hate relationship with your job.

Another expression that relates to opposing feelings is, “There is a fine line between love and hate.” A person can go very easily from loving to hating.

Star-crossed lovers are very different than those in a love-hate relationship. These types of lovers want to be together, but everything seems to keep them apart -- even the stars. This expression comes from the belief of some cultures that the stars control our futures.

The Merriam-Webster Online Dictionary says “star-crossed” was first used in 1597. Probably the most famous star-crossed lovers are William Shakespeare’s Romeo and Juliet.

Star-crossed lovers never seem to get together. So they are rarely on the rebound. A rebound relationship is the first relationship someone has after he or she has ended a serious, long-term relationship.

The term “rebound” used in this way dates back at least to the 1830s. Writer Mary Russell Mitford wrote, "nothing so easy as catching a heart on the rebound."

People on the rebound are easily hurt and vulnerable. So they often make bad decisions in choosing a new love interest. Instead of getting involved with someone else right away, someone on the rebound probably needs some time alone, as well as distance from their ex -- long distance.

This time and distance alone to heal is not to be confused with a long-distance relationship.

People in a long-distance relationship live very far apart from each other and don’t see each other on a regular basis.

A long-distance relationship can be perfect for someone who likes their own space. But it can be lonely for a person who wants to spend a lot of time day-to-day with their partner.

A long-distance relationship can also be very expensive if the two people need to buy airplane tickets to see each other.

Of course, every relationship has its ups and downs, good times and bad times. But a tumultuous relationship has very high ups and very low downs. Even though a tumultuous relationship can be troubled or even violent, it appeals to some people who like passion and drama.

But after a while, all that passion and drama can destroy the soft, gentle feelings the couple had toward each other. They eat away at the couple’s love like poison, and the relationship turns toxic.

Now, let’s talk about the couple who can’t seem to decide whether to commit. They are in an on-again, off-again relationship. Sometimes they are together, sometimes they are not. You can also call these relationships on-off or on-and-off relationships.

A love triangle does not describe a person who loves geometry, but it does involve the number three. A love triangle describes three people who have feelings for each other but those feelings do not always match.

So let’s say Barry, Gary and Sherry all went to college together and are very close friends. However, what Sherry doesn’t know is that Barry is deeply in love with her. Meanwhile, she is in love with Gary. But Gary doesn’t know about either of his friends’ true feelings. He likes them both. What he really loves is baseball.

One day, Sherry takes a chance. She tells Gary how she really feels about him. Gary is surprised … but then he realizes that he loves Sherry, too. To show her how special she is to him, he takes her to a baseball game. A television camera at the stadium catches them holding hands, and then kissing.

When Barry sees his friends in a lip-lock on TV, he becomes very depressed. Now he is no longer in a love triangle. Now he is experiencing unrequited love. This is a one-sided love. One person falls in love with another, but the feelings are not returned.

That night, he runs through the rain to Sherry’s house. He knocks on her door and, dripping wet, begs her to choose him over Gary. This is a bad decision. Sherry tells Barry that she does love him, but she’s not in love with him. The two are very different.

Sherry has just said the worst thing for someone in love to hear. Barry is crushed. He decides to move to New York City. He joins a rock band and sings about his broken heart.