Looking for something like the grim reaper or the lady in red but without the political aspect. Basically i want a romance novel that focuses on the couple and his military journey.
Also don't recommend me popular stories like a fresh start as i have probably read it already.
Since we don't know which popular stories you have read, I'll ignore that requirement. You can decide whether to read a story or not.
Argon's https://storiesonline.net/s/17041/the-return-of-thomas-grey is currently posting, almost complete and fits your description. Several of the stories in that https://storiesonline.net/universe/102/anthony-carter also fit, https://storiesonline.net/s/58363/joerg-isebrand fits marginally - most of the romance is in the last few chapters.
While not a long story, 'Star Crossed Lovers' by HLD explores the effect a military career has on two military personnel who fall in love. Worth reading.
https://storiesonline.net/s/55089/star-crossed-lovers
the butterfly and the falcon : Set during the terrible events of the Spanish Civil War of 1936/39. A young foreigner enlists in the Republican Air Force to meet his match, a woman of the radical Anarchist Brigade.
Basically i want a romance novel that focuses on the couple and his military journey.
Probably not exactly like what you're wanting, but I recommend the Prince Roger series by David Weber. (It does end up being a love story, after all.)
How about Lois McMaster Bujold's Cordelia's Honor?
It is comprised of two parts: Shards of Honor and Barrayar. Together they form a continuous story following the life of Cordelia Vorkosigan nee Naismith from the day she met her then-enemy Lord Aral Vorkosigan through the boyhood of her son Miles. (cited from Publisher's Note).
HM.
Basically i want a romance novel that focuses on the couple and his military journey.
Ok, this will be a stretch. It's nothing like a novel. In fact, it's flash fiction. It was written for a Writers Digest contest that had a 750-word limit. But you can read it in about 5 minutes so if you don't like it you wasted 5 minutes.
A suffering war veteran returns to his childhood home, and two surprises.
"Coming Home" - https://storiesonline.net/s/70300/coming-home
Kelly by Morgan
G.I. rescues naked teenager from Russian KGB. She in turn saves his life and goes on to become youngest general and most decorated veteran in history.