I've noticed that most SFR requires tentacles and other wriggly bits for most people but I grew up on Anne McCaffrey so I lean towards cleaner Science Fiction so here is my list of up and coming Science Fiction Romance that is also happens to be clean.
The Heights of Perdition by C.S. Johnson
Be ready to be inspired. This Christian author isn't afraid to have religion in her Science Fiction. She is an English teacher like me so I can relate.
We have a Romeo and Juliet set up here where a pirate takes on a military pilot. But maybe their two worlds aren't so far apart.
The whole series is complete so if you get hooked you don't have to wait.
Cold Welcome by Elizabeth Moon
Okay, Elizabeth has been around for a while but she is still pumping out the science fiction romance. Love Vatta's story and I grew up reading her as a kid. Still awesome.
Vatta is now an Admiral and gets stuck on a planet with a whole bunch of strangers.
This is just the start of the series so I expect another dozen or so as Elizabeth can certainly keep a series going.
This is Me by C.E. Wilson
A best selling author you know it is going to be good.
Chloe is protected by an Android and it all turns into a love triangle with man and machine in the ultimate battle, for her heart.
This is a stand-alone so no more after this and it is more NA than clean, it has all the sci-fi elements you could wish for.
Eight Million Gods by Wen Spencer
One of my personal favourites and I've been following her posts of lava flows in Hawaii. Wen has several clean Science fiction series.
Nikki is writing really crazy stories only to find out that they are really happening.
She has other series but they are a M instead of PG so that is why I haven't put those up instead.
Worlds away by J.L. Hendricks
This author calls her book a PG 13 which is clean enough for me. It is certainly a bit darker than the other books on this list but still clean.
Taken as a slave she has to choose to be a slave or the commander's mate.
I like these kind of stories so I'm glad there is a clean version I can read.
Firebird by Kathy Tyers
This has recently been re-released so sort of new.
Captured by the enemy, death is her only option, but instead she finds someone who can literally see into her soul.
A complete series and great to see the new packaging. Loved it the first time, will probably buy the new set as well.
Starfall by Brenda Hiatt
Want something a little sweet then this is perfect. I love the 'aw sweet' story of this series. These are quick books to read so great for sneaking in some love and happiness into your day.
M is desperately nerdy but that is all to change and hopefully it will bring her happy ever after since she is now a Martian Princess.
Branching out from her usual regency romance we see what she can do with space. Pun intended.
The Survivors by V.L. Dreyer
A fellow Kiwi I had to add them to this list. This is a post zombie series set in New Zealand, which I love.
Sandy is a survivor but can she live?
Several books in this series already so looking forward to that. These books are easy to read, which is a good thing for me as I'm dyslexic.
Cinder by Marissa Meyer
A rewrite of fairy tales but with cyborgs and moon queens, Marissa is a solid favourite on my shelf. I've re-read Cinder three times now so has the chops to stand amongst the greats in my books.
Cinder is a cyborg who fixes things. If only she could fix the disease that is killing friends and family. In steps prince charming and her secrets are big enough to swallow them both whole.
This series is complete with some extras thrown as well. This is one that needs to be a movie it that good. Check out the mock movie trailers on Youtube, they are awesome.
The Little Cyborg by J.M. Page
This light book is a mix of sci-fi and sweet contemporary romance. Like Cinder we have a prince and a cyborg so a great read by don't expect Hemminway.
Celine and Ben have to overcome a life time of prejudice to be able to be together.
There are a few books in her back list so if you enjoy this there is more to come.
Honourable mention is the Host by Stephanie Meyers but I think it sucks that she promised us a sequel and we are yet to see it. Please write it. I want to see how the series ends.
FYI - the links are from both UK and US so go to whichever store is your local one.
Model:Serenity by Nix Whittaker
This is an extra because it is my own book and of course I'm biased. This is the first in the series but I have other sci-fi romance series.
Aaru wants to be a mother so bad she isn't willing to wait for the man of her dreams. With technology on Ardin it is a simple matter. Now the father of her baby is on her door step and the government wants her and her baby and that dream is about to be shattered.
Four books in this series.