How do I bring up talk of engagement?

sounds to mke like when he brought it up he was looking for some kind of response from you, you said you acted septical, which probably made him think that you didn't feel the same way so he backed off the idea till he feels you more ready... if youre unable to talk to him, maybe write him a letter telling him that at first you didn't know how to react and if he was serious you want to, or you can just say, "remember months ago when you brought up asking me to marry you...." or just pop the question yourself.. my guess is when he brought it up, youre response made him think it wasn't what you wante so he didn't want to push it, doesn't mean his feelings have changed just doesn't want to push you... just go for it!