If you wanted to find out whether your partner is loving you really or not, just do it this way.
Note the things that you generally do to make your partner happy. Be sure that your partner is liking that activities very much. Then you start avoiding to do those now.
Example : If your partner loves to have coffee with you and you both are regularly habituated to that, then one day, you break that procedure. Make your partner believe that you are breaking it with no intention and only because you are busy in some other work or involved in some tension. You should still talk to them very casually with no sort of differences.
Then one fine day, they themselves come to you and remind about the coffee matter, then you can realize that they are still thinking of you, likes to share with you and moreover remember that they still love you.