He doesn’t want to take the chance of missing out on other opportunities.
Though you may have been seeing this guy for one year, he may not necessarily believe that you are the person that he wants to spend the rest of his life with.
In essence, when he is able to hide or even deactivate his dating profile so that he can focus all of his attention on you, he is showing that he is more interested in you than other girls.
If he is still talking to other girls on the dating site and meeting them, there is a good chance that he is just as interested in you as he is in them.
They would typically not compliment you if they didn’t truly believe that you were appealing.
The issue isn’t so much with how honest guys are when complimenting girls on dating sites, it’s more so with how much they may exaggerate their compliments.