No one can say NCIS isn’t a successful TV show. With 20 seasons and counting, it has become downright iconic and spawned multiple spin-offs.

The original series has a proven episodic formula with compelling crimes and intriguing mysteries.

What it doesn’t have much of is happy relationships.

If you are a shipper, be warned. With rare exceptions, long-term romances are doomed on NCIS.

Couples are either teased but never get together, only get together offscreen, or break up far too fast to be satisfying to the fans who root for them.

And if a couple somehow miraculously does end up in a stable, loving relationship, well, the clock is ticking because one of them is likely to die.

So read on as I list the NCIS couples that infuriated, depressed, or simply broke my heart.

Gibbs and Shannon - DEATH

NCIS started with a tragic love story, albeit mostly offscreen and shown in flashbacks.

Leroy Jethro Gibbs' romantic history on the show begins with tragedy and never gets much better.

Gibbs' first wife, Shannon, and their eight-year-old daughter, Kelly, were murdered by a Mexican drug dealer after Shannon witnessed a murder.

During NCIS Season 3 Episode 24, we're told that the murder took place on the last official day of Operation Desert Storm while Gibbs was still deployed as a US Marine.

Gibbs never gets over this epic loss, and it clearly shades every other relationship or attempt at a relationship he has for the rest of the series.

Gibbs and Diane - DIVORCE and DEATH

Gibbs did marry again, actually several times, but none of those relationships lasted.

Out of all of his marriages, Diana was my favorite ex-wife.

Although Gibbs liked Diane enough to marry her, she loved him and realized she would never be able to compete with his love for his late wife, Shannon.

Diane had a sarcastic wit, and she never backed down from a good verbal sparring match with her ex. She later went on to marry and divorce one of Gibbs' best friends, FBI agent Joe Fornell.

Unfortunately for Diane, even being in Gibbs' vicinity was unhealthy.

During NCIS Season 12 Episode 11, Diane was shot in the head and instantly killed by the sniper bullet of one of Gibbs' enemies, Sergei Mishnev.

You could say that Diane's murder indirectly led to her and Fornell's daughter's death, and then Fornell became just as lonely as Gibbs. The entire storyline was more depressing than entertaining.

Gibbs Many Other Loves and Losses - DEATH, DIVORCE, and BREAKUPS

Gibbs has loved and lost so many times that I could dedicate this entire article to it, maybe even have to make it a two-parter.

Instead, I’ll just hit some of the highlights, or lowlights depending on your point of view.

During NCIS Season 4, it appears that Gibbs is in a somewhat serious relationship with Army CID agent Lt. Col. Hollis Mann, played by Susanna Thompson.

I liked Hollis and had high hopes for this pairing. She was low drama, and she and Gibbs had chemistry and plenty in common. Although this couple looked promising, it ended offscreen before the following season began.

Gibbs also had a romantic relationship with his former partner and later NCIS Director Jenny Shepherd, played by Lauren Holly.

Although their relationship was complicated, it was over for good when Jenny was shot and killed in a firefight during NCIS Season 5 Episode 23.

Did Gibbs and Jack Sloan, played by Maria Bello, have a romantic relationship? It’s difficult to tell.

But when the forensic psychologist left the series in NCIS Season 18 Episode 8, the two did share an onscreen kiss, and that's as much as fans ever got from this potential pairing.

Leon and Jackie Vance - DEATH

Director Leon Vance and his wife Jackie were a happy, married couple with two children, so why Jackie's death took me by surprise is a mystery. Happy couples don't normally survive in the NCIS world.

During NCIS Season 10 Episode 11, Jackie ended up being shot and killed, collateral damage during the assassination of Eli David.

Jackie died, leaving Leon, a widower, and her two children without their mother. Predictable? Only on NCIS, and goodness knows, it was depressing.

Tony and Ziva - DEATH, but not

The majority of Tony and Ziva’s onscreen moments can be described as romantically ambiguous, and yet I spent years rooting for them to get together.

Fans were teased for far too many seasons with a Tiva pairing that led nowhere. There were longing looks, movie nights, and numerous times they saved one another’s lives.

These two went undercover as married assassins during NCIS Season 3 Episode 8, leaving fans wondering why Ziva referred to Tony as “my little hairy butt.”

In NCIS Season 7, Tony admits he doesn’t think he can live without Ziva when they believe she may have perished, but nothing much changed in the aftermath.

And after getting even closer in Germany on NCIS Season 10 Episode 21, the installment concludes with the touching moment of Tony reaching for Ziva’s hand, a moment I truly believed meant they were headed for more.

But once again, it turned out to be more of a tease than any real movement in their relationship, at least onscreen.

Over and over again, the series gave shippers just enough to keep us coming back for more but never enough to leave us anything even close to satisfied.

And when they finally did get Tony and Ziva together, as they must have to produce Tali, it was done completely offscreen because Cote de Pablo had left the series!

Talk about a slap in the face to long-term fans who spent years rooting for this couple.

Tony didn’t even find out Tali existed until she was a toddler, and Ziva was presumed dead, and that's the first confirmation that fans had that these two had slept together.

Thankfully, Ziva was alive and hiding, and this family was eventually reunited, but frustratingly, more of this couple exists in our imagination than onscreen.

McGee and Delilah - ALIVE and WELL

Honestly, I was never much of a fan of McGee and Delilah, so it’s just my luck that they ended up as one of the very few happy, long-term relationships on the show.

They survived tragedy when, on NCIS Season 11 Episode 13, Delilah was badly injured and ended up wheelchair bound.

But McGee and Delilah are likely the healthiest couple on the show, now raising their twins, Johnny and Morgan.

Jimmy and Breena - DEATH

NCIS has a habit of giving their secondary characters better love stories than their leads, which is a shame. Jimmy and Breena were a sweet couple, but in true NCIS fashion, no one can be happy for long.

It's revealed on NCIS Season 18 Episode 7, that Breena died of the Covid-19 virus during the pandemic, leaving Jimmy to raise their daughter alone.

It’s great to see Dr. Jimmy Palmer get more of his own storyline, but it’s a lousy and depressing way of making it happen.

Nick and Ellie - BREAK UP (we think)

Nick and Ellie felt like Tony and Ziva part two.

They had loads of chemistry. They went on dates that they didn’t call dates. They even did goat yoga together!

On NCIS Season 17 Episode 14, Torres even physically threw Bishop out of the way of an oncoming vehicle and took the hit himself. If that’s not love, I don’t know what is.

But in the end, Ellie pulled a Ziva and disappeared on an undercover mission as actress Emily Wickersham left the series.

Were Nick and Ellie in love? More than partners? Friends with benefits? We really don’t know and it makes me wonder why I ever bother investing in any potential couple on NCIS.

How about you, NCIS fans? Are you a shipper? Have you had a favorite pairing on NCIS break your heart?

Hit that SHOW COMMENTS button below to share, then check out Everything You Need To Know About NCIS Season 21 here at TV Fanatic. 

C. Orlando was a TV Fanatic Staff Writer. Follow her on Twitter.