I recently read this story (recently meaning within the last two years), but can't for the life of me remember the name of the books. It was part of (at least) a trilogy, of which I read two. The sequel containing the conclusion had yet to appear. The books I read felt like the characters had appeared before, but in a different setting, so it may be a longer series.
The setting was that humanity is distributed all over the galaxy but has found an (initially assumed to be) alien life exponentially multiplying. They "infect" a planet and turn it within some short timespan into producing millions of rockets which they send out blindly in order to infect new planets. These aliens are not intelligent at all, all they do is multiply and spread and are described as vaguely rat-like. Humanity starts to fight them but seems to be fighting a loosing battle, since they can't contain it. The story had the weaponization of some bubbles in spacetime (dead or empty space) and also humans were able to teleport over vast distances, depending on personal ability (the most able were able to jump ten thousands of lightyears) and live for very long.
The story (partially) follows a husband and wife that are the captain of the ship coordinating the defense against the aliens. They may have been from Earth and pulled into it by the existing humanity, but I may be mixing things up. I think the wife might have been trapped in one of the dead space bubbles at the beginning of the first book I read and her husband figured out how to destroy (and later create) these bubbles. Most of the story happens in space, quite a lot of it in conference rooms aboard the space ships.
During the course of the two books the aliens are found to be genetic experiments created by some strand of humanity and then forgotten. The descendants of those humans are still roaming the stars trying to eradicate them by nuking entire planets, a futile effort since they replicate much faster. Those humans still have normal lifespans and they have been doing so for more generations than they can remember.
There is also a race of bona-fide aliens, which most of humanity does not know about, only some very old humans left from when they struck a deal with them not to bother them (one of which is helping rally humanities production into producing war ships and seems to be the overall coordinator of the defense). I think these aliens look like the stereo typical grey aliens in popular culture, which is what spawned those myths in the first place (in-universe).
I thought of this story today and started wondering if the sequel had come out yet, but I can't check since I don't remember the name or author.