4.5 stars
I've waited for this book for a long time and I'm vey happy the author finally published it.

It was a complicated love story, where the MCs had to deal with conficted emotions, when the grief for the loss of a beloved lover is mixed with guilt, creating a combination of feelings that were not so easy to deal with nor to overcome.

Elijah is happily in love with his husband, Landon, they have a good life, until an accident at the lake, during a romantic evening, will take Landon away, leaving Elijah alone, hurt and confused about what really happened.
Silas has been sick his whole life: his heart has reached the end and he's not high in the list of recipients, so he's reisigned to die. His wife takes care of him, works 2 jobs to make ends meet and she's not ready to loose him.
The two men met a couple of months after Silas received a new heart.

Let's clarifying something that could put a lot of readers off this book: Silas is a cheater.
Yes, his marriage was not happy, his wife had a toxic behaviour that he started to notice only after the transplant (even if there have been hints before that he didn't entirely acknowledge).
Yes, his attraction for Elijah was a heart memory, out of his control.
But he chose to pursue the other man, before ending his marriage, so yes, Silas is a cheater.
And he's also one of the most wonderful character written in MM romance.

I adored him, he's precious and brave, he didn't understand what was happening to him, but he wasn't scared to ask for more. When he felt that Elijah meant so much to him, that what he was feeling was strong, he didn't hesitate to put an end to his marriage to be with him and he never hid him.
Elijah is devasted by the loss of his husband, but Silas made him feel alive: Silas may have been the more fragile between the two of them, but he also had the ability of pushing Elijah out of his comfort zone. Elijah is completely smitten and he doesn't understand how it's possible to feel so much so soon. I loved his protective and caring side.

Their relationship is truly amazing. The connection, the banter, the chemistry, the ability to understand and support each other (and that had nothing to do with Silas' new heart), their intimacy and the feelings they had for each other.
Every little touch, every look or kiss is sweet and powerful at the same time.
The sex scenes are on another level, strong, consuming and so so intimate: Elijah is a little more dominant and Silas is totally under his spell. They melt into each other and nothing can break their connection (literally nothing or no one! The scene in the laundry was intense!). None of these scene was just sex, it was so much more since the first kiss.

What prevented me from giving 5 full stars:
I almost gave it 4 stars, honestly because there are too many things about the darker part of this book that were left unsaid and that I would have liked to be explained instead. 
For example,

since when Stacey was working for the organization? Was she forced in order to have a heart for his husband? Otherwise, how could have she afforded to buy a heart from the black market?

 
Moreover

what was the point of Landon's secret? Did he not trust Elijah about the money? The author said his family never loved him but asked constantly asked for money. I'd expected for them to pester Elijah about the inheritance, but he never had contact with them again...

But the part that bothered me the most was the fact that

after all the months they spent apart since the break up (by the way I honestly loved it and I second all Silas' reasons for it), Elijah still never clearly said that he loved Silas because he was his person, and that Landon's heart wasn't the reason for his feelings.

I would have love for him to be more determined about that, to give the other man the reassurance he needed, because Silas was amazing and him being so perfect for Elijah had nothing to do with his dead husband's heart. 
The heart brought them together, but it was not the reason for their love: this should have been said more explicitly.

Anyway, it was a really great book: the author is planning another book featuring two secondary characters of this story, I hope we'll have glimpses of Silas and Elijah too, because, honestly, I want so much more of them.

Highly recommended.