Your Dog is Being Protective
Another reason why your dog might be doing this action a lot is that they become especially protective when you are around other people or animals.
Your Dog Feels Safer
Most dog breeds were bred to work alongside their owners and feel more secure when they are in a group.
Your Dog Wants Your Attention
Your dog is trying to get extra attention from you. This behavior would be more likely if you have not given your dog attention for a while.
Your Dog Is Happy
Yes, laying on top of you makes your dog happy. You have the love hormone Oxytocin to thank for that.
Your Dog Is Expecting Something
Most pets love routine and so the cause of this behavior could be that it is waiting to get something from you.