My boyfriend calls me by his last name?

To start off me and my boyfriend have been together for some time and we truly believe we have found our other halves and that we are meant to be no matter what

As of lately my boyfriend has been saying my full name when we’re just hanging out, or if we’re out in public, or if we’re saying our goodbyes for work/school. He’s been replacing my last name with his and he constantly kisses my ring finger. What does this mean?