As to whether or not it is a good idea for someone to go along with another person’s emotional state can all depend on what state they are in. If this person is happy, embracing the same state is likely to have a positive effect on one’s wellbeing. On the other hand, if this person is angry or even miserable, embracing this state is unlikely to do them any good. There are then going to be times when it will be a good idea for one to allow their emotional state to mimic another person’s emotional state and times when it won’t.
However, even though this is the case, one may find that there are times when they are unable to control how they feel. Ergo, irrespective of what is going on for another person, they will end up being drawn in.
This is not going to be a problem if another person is in a good place, but it will be if they are not. When it comes to the latter, it might be necessary for one to get away from the other person.