Big Bang Theory entertained viewers for 12 seasons as they enjoyed watching a group of geeky scientists and physicists blurt out words we couldn’t understand and discuss comic books, Star Trek, and Star Wars in greater depth than most people ever care to do.

The series was, for the most part, totally and utterly hilarious as we watched the guys try and meet girls, the girls put up with the guys’ antics, and the group go through everything from starting families to winning the Pulitzer Prize. But like any other sitcom, there were a few tough, touching, and even heartbreaking moments.

As we finally accept that the series will not be returning with new episodes, and enjoy continuing to hear Sheldon’s voice narrating the spin-off series Young Sheldon, here’s a look at ten times the series broke our hearts instead of made us laugh.

When Amy Broke Up With Sheldon

Sheldon might have taken Amy for granted one too many times, but when Amy decided to call it quits, clearly a difficult decision for her, it gave us all the feels. It shocked Sheldon, finally making him realize what he had.

Or maybe he knew all along? Because breaking our hearts even more is when it was revealed that Sheldon had been keeping an engagement ring in his drawer, with obvious plans to give it to Amy some time soon. Of course as we all know, they eventually got back together. Phew!

When Zack Wanted Penny To Be His Surrogate

It seemed like an almost silly idea: that Penny’s ex-boyfriend would turn up, asking Penny to be a surrogate for he and his wife who are unable to have kids due to his infertility. But what really makes this story break our hearts is when Penny actually considers it and has an important discussion with Leonard about not wanting to ever have children of her own.

Leonard’s disappointment as he tries to rectify his love for his wife with his obvious desire to be a father is truly heartbreaking. Those who watched the show right through to the end know that, spoiler alert, Penny doesn’t go through with it (and they change their mind), even after Leonard comes to terms with her decision. And Penny reveals that she’ s pregnant in the series finale, thanks to a happy accident.

When Sheldon Gave His Nobel Prize-Winning Speech

Anyone who watched the series from the beginning who didn’t shed at least a few tears at Sheldon’s speech when accepting the Nobel Peace prize for physics is a complete monster! It was so touching and selfless, which are two qualities Sheldon had rarely, if ever, shown before. Instead of touting his abilities, smarts, and intellect, he turned the focus to his friends who all contributed to his success in different ways and allowed them each to take a bow.

It broke our hearts mainly because it was a major breakthrough for the character, and signaled the end of the series that has been part of the primetime line-up for 12 seasons. Photo: Michael Yarish/CBS

When Amy Told Sheldon People Just Tolerate Him

After Sheldon angers his friends by acting selfish, downplaying Leonard’s and Penny’s baby news, he has a heated argument in his hotel room with Amy. Livid, Amy finally tells Sheldon that he takes his friends for granted when really, they just tolerate him. Ouch.

Sheldon was clearly hurt by her statement, and finally realized that he was being a jerk and thinking of no one but himself, as he has throughout much of his adult life. It was a rude awakening for Sheldon, but just in the nick of time for him to use his Nobel Prize-winning speech to make good with those who have supported him along the way.

When Sheldon Mourned the Death of Professor Proton

Professor Proton, who had a kid’s science show when Sheldon was growing up, was a role model for him. He completely related to all of the science stuff that was discussed on the show and was glued to the television whenever it came on. Then, later in life, Sheldon actually got to meet the real Professor Proton.

And even though Professor Proton had become nothing more than a washed out former TV star, Sheldon still idolized him. So when he learned of Professor Proton’s passing, Sheldon was understandably quite upset. In fact, it’s one of the only moments in the show when we truly see real sadness in Sheldon.

When Sheldon Hid In the Bathroom at His Own Surprise Birthday Party

Sheldon told all of his friends that he didn’t like surprise parties, but they didn’t listen and threw one for him anyway. It completely backfired as Sheldon ran out of the room and hid in the bathroom for the remainder of the event.

Penny being the one who was finally able to get through to Sheldon and console him in his time of need was one of the sweetest moments of the series. But it was still so sad to see how Sheldon’s past and growing up without many, if any, friends, had really affected him.

Whenever Leonard Saw His Mother

It was hard not to feel Leonard’s years of pain and neglect every time he came in contact with his cold and distant mother.  A respected neuroscientist and award-winning psychiatrist and author, she used Leonard as her guinea pig through much of his life, experimenting on different ways to parent to analyze the outcomes for her research.

She continued to do so even through adulthood, drudging up painful memories for Leonard. So whenever he saw her, it was heartbreaking, particularly in the last scene with the two together when Leonard finally realized that he needed to forgive her in order to move forward. They then embraced for likely the first time in a long time, if ever.

When Leonard and Penny Broke Up

Viewers all knew Leonard and Penny were destined to be together. So when they broke up after Leonard had worked so hard to win her affections, it was heartbreaking.

Penny sobbed like a child because of it. But what was even more heartbreaking that it wasn’t because they fell out of love, but because Penny believed that she couldn’t be what Leonard needed, and felt she wasn’t good enough. And to twist the knife in further, it was after Leonard told her he loved her for the first time. Excuse me while I get something out of my eye.

When Howard Revealed Details About His Past

Break out the tissues. Howard sat the gang down and told them the story of his absent father, who abandoned he and his mother when he was 11, leaving him to spend much of his adolescence longingly waiting for his father’s return (that never came).

On his 18th birthday, Howard’s father wrote him a letter, but he revealed to the group that he destroyed it before ever reading what it said. However, not before he allowed Sheldon to read the letter.

The gang than touchingly run through scenarios with Howard about what the letter might have said. But we never really find out the truth, nor does Howard. And everyone else is just fine with that.

When Howard’s Mom Died

Arguably the saddest moment of the entire series was when Howard found out that has mom passed away. What made it especially sad was that all of the emotions were real, as the actor who voiced his mom passed away in real life.

It broke our hearts not only to see Howard’s reaction, but that of all of his friends. Even Sheldon was surprisingly good at consoling his friend, relating to Howard to lean on his friends to help him through, as Sheldon didn’t have any friends to support him when his own father passed away.