obsessively

An obsessively person or thing fixates or becomes extremely interested in something to an excessive degree.

People often use "obsessively" when talking about hobbies, relationships, or activities they find themselves constantly thinking about. For instance, someone might say, "He's been playing the guitar obsessively since he got it." Here, the speaker means that this person has spent a lot of time practicing and thinking about the guitar. Or, in another context, "She obsessively checks her phone for messages." This means she keeps going back to check her phone repeatedly, often even when there are no new messages.