I would say that Rodrigue is truly in love. Chimene's love is more open to discussion.
The reason for both of these answers is honor and duty. Rodrigue says that nothing he's done would be worth anything without Chimene—but early on, honor drives him to kill her father, which drives a wedge between them.
Chimene definitely loves Rodrigue later in the play, but early on, may have first agreed to marry him, then rejected him, due to honor and duty owed her dead father. Her love, then, has more barriers to negotiate on the road to reality.