hey bro, so get you, this is what happened to me with my piano. i analysed it and am commited not to let it happen to my guitar, there where 2 reasons

1) when i had babyish piano i was much more into it, once i got a good one i lost intrese. what i believe it comes from, is that when you have your cheap one, you are motivate and have what to wait for, but once you got the good expensive one, its like you reached the top of the mountain, and its like, what now?

2)start learning something new, when you stop and play over and over the same few chords and the same strum, no wonder you get bored. Always challenge yourself to something new, something you couldnt do yesterday. it keeps you young, fresh and motivated!

good luck for you and everyone with this, i hope it helped!