It just means you have a crush on the person you’re running with! 😂
Seriously, though, heart rate responds to an almost infinite number of influences. If it’s not the extra effort of carrying on a conversation that’s elevating your HR, it may be some other psychosocial influence. I will say, though, that not being able to sustain a faster pace with a companion is not normal. There’s tons of research showing that endurance athletes perform better in a group.