What's the meaning of "deep" here?

Question

This is a passage from the song Hero by Enrique Iglesias:

Would you swear, that you'll always be mine?

Or would you lie? Would you run and hide?

Am I in too deep? Have I lost my mind?

I don't care you're here, tonight

This is the fourth paragragh and in the third line "Am I in too deep? Have I lost my mind?" What does deep mean here? I looked up OALD and it seems like definitions #10,11 and 14 are all closely related, but I'm unsure which meaning is most appropriate or does it mean something else that's not included in this dictionary?

Answer 1

While some of the definitions and idioms mentioned/linked are relatively close approximations, they all miss the specific idiom "in too deep", referenced here: (to) be in too deep

This generally references being involved in something so thoroughly that you become unable to extricate yourself (you can't escape); it is meant to allude to the experience of being in a mud bog or shallow quicksand (not enough to bury you, but too deep to escape), or to wander into a cave or woods so far that you no longer know how to return.

Note this is not precisely the same meaning as being "in deep water" or "being thrown into the deep end"; these latter two idioms indicate overwhelming challenge or great difficulty, or being forced to face a challenge beyond your experience or comfort.

Answer 2

None of the numbered definitions at the mentioned link seem quite appropriate. Instead, refer to some of the idioms at the end:
• in deep water or in deep waters (informal) in trouble or difficulty
• jump/be thrown in at the deep end (informal) to start or be made to start a new and difficult activity that you are not prepared for

These idioms derive from the situation of a person, perhaps a non-swimmer, in difficulty in deep water or the deep end of a swimming pool, as the person struggles to breathe and stay afloat.

That is, “Am I in too deep?” might mean “Am I in waters too deep for me?”, or “Am I in ‘over my head’?”. Another possibility for the intended meaning is “Am I more deeply involved than I should be?”, in which case numbered definitions 10-12 and 14 would apply.