I read a book about ten years ago that was about superpowered soldiers and their relationship. I believe they were powered naturally but then the government took them and enhanced them. This was a normal working of their society, although I believe a goal of the two men was to change the way things were done to be more compassionate and ethical.
They were fighting a war against aliens who came through portals.
The main character had some sort of power to affect gravitational fields I believe. Or at least, some sort of invisible energy field that he could mess with. He was very powerful. He could also overheat due to his powers, which was very dangerous and could result in him becoming a mini bomb. At the end of the book, he actually starts overheating while at home, his family/friends all run outside but his lover stays and talks him through it. They don't end up dying.
I don't specifically remember the powers of the lover, but I think he had super speed, but only as part of it. He wasn't just a speedster. I think he was a redhead.
At the beginning of the book, they get reunited. The lover had been thought dead as he had gone through to the other side of a portal just before the portal closed/blew up. He spent several years fighting on his own on the alien side and at the beginning of the book makes it back home through another portal.
They learn how to use their powers together, which is considered very dangerous, but the government is very interested in it. There is a scene where they go to a military obstacle course to practice.
There is a scene where terrorists attack a marketplace when they are sitting outside a cafe eating cheese. They take down the vehicle (I think it's an armored truck) together. The main character cracks the engine block using his powers.
Does anyone know the title and author of this book? I remember reading it as an e-book.