Love/Not Love People often asked Remus how he could live with and so obviously adore a man such as Severus. War hero or not, the man was still snarky, sarcastic, and usually unpleasant. Remus was kind, easy going, considerate, and enjoyable to be around. The exact opposite of Severus. Many people commented that Severus did not even give the appearance of returning Remus' affections in any way.
Remus, however, knew different. No, Severus was not a "hearts-n-flowers-and-candelight-romance" type of man. But in small ways every day Severus displayed his love for Remus. He endured without complaining (much) Remus beloved cats, even going so far as to make food and special supplements to keep them healthy. True, he may explains it by scoffing "Keeping them in optimum condition is advantageous for me since it eliminates you worrying about their health or weeping and wailing about their passing!" He always had a cup of tea, spelled to stay hot and fixed just as Remus liked it on the nightstand by their bed for when Remus woke. Remus would always mumble his thanks as he sat up bleary eyed. Severus dismissed his thanks with "No thanks are necessary, Remus. I just wish to assure that you will rise before noon and not leave all the chores for me!" Remus health was much improved thanks to the improvements Severus made to the wolfsbane potion, and the analgesics he brewed specifically for him. When Remus groaned his appreciation after his transformation, knowing that he would not have to spend several days recovering, Severus only sneered and said, "As you should be Remus! However, I did it for my own benefit not yours. I merely wished to ensure that I would not be playing nursemaid to an invalid wolf several days each month!
Severus may rarely say the words, but in these and many other small ways, he showed Remus how he felt about him. As far as Remus was concerned, he wouldn't change Severus' expressions of love for all the romantic "hearts-n-flowers" in the world!