Stumbling Block and My Weaker Brother

Something happened awhile back that got me ta' thinkin'. Yes, sometimes it happens.

The Bible talks about not being a 'stumbling block' quite a few times. It also addresses making decisions in consideration of our 'weaker brother'.

(Just a couple of references [feel free to check our Biblegateway.com for more]:
Romans 14:13Therefore let us stop passing judgment on one another. Instead, make up your mind not to put any stumbling block or obstacle in your brother's way.

1 Corinthians 8:9Be careful, however, that the exercise of your freedom does not become a stumbling block to the weak.)

A scenario came up in which I realized I could be a stumbling block to a weaker brother, even though it might look like I was trying to be the opposite. For example, if I said to a friend who is working hard at losing weight due to a recent diabetes diagnosis, "Would it be ok if I ate ice cream while we visited?", it would look like I'm considering my friend. BUT am I really if I'm putting the ball in her court? I'm now forcing her to deny me something instead of me choosing to sacrifice on her behalf. Same thing goes if a friend calls and invites me out saying, "Would it upset you if I drank alcohol?" Now I'm having to tell her yes or no. She doesn't know if I'm a weaker brother in this area of life. She may be attempting to avoid being a stumbling block, but...
...aren't stumbling blocks stumble causing because the person can't see them or maneuver around them well?

...aren't weaker brothers weak because they lack strength in a particular area?

If we truly want to avoid being a stumbling block or we want to truly consider our weaker brother, shouldn't we shoulder the responsibility instead of putting it on them?

Isn't that really the heart of the matter?