I would be extremely careful about what you do. Dont let a phase ruin something that you have which is so good. Maybe a little diversity is good in your relatinoship? you dont want to date yourself do you?
Its up to you to stay together or not to, but in all fairness something similar to this happened to me (on the other end), and I would have appreciated talking to my ex about it. I think its only fair that you let him know your feeling. Trust me, if you dont, he will feel like he could have done something, but you wouldnt talk to him about it.
Maybe the conversation to lead to you guys doing more things in common, maybe he thinks the same and you dont know...The only way to know is to talk to him about it.
Just make sure you dont decide on a whim
