Ok, coming back to touch on another point.
ISFJs need
time. Time to think, time to self-examine, time to figure out how they really feel about something. You can't give them a question and expect them to immediately spring back with an answer. I'm not saying that he's going to ponder the benefits of 1% vs 2% milk in the dairy aisle for an hour, but if it's something important, he's going to want to make what he feels is the right choice. If he's rushed into anything, he's going to have feelings of regret, and possibly resentment, that he wasn't allowed to think about it.
When I pose an issue to my boyfriend, the discussion seems to take place in stages. First I lay out what the issue is and we talk enough for him to get the general idea of what I'm saying. Then that evening or the next day, we talk a little more for clarification of so he can make sure that he has a correct grasp of what the issue is. Then throughout the following week, he'll bring it up every so often to talk to me about his thoughts concerning the issue, basically touching bases with me to see how I feel about the conclusions he's come to, and he'll take what I say into consideration and go back to sorting things out.
This process will continue for as long as it has to until his thoughts have arrived at a final resting place and he's made his final decision about what his true feelings and opinion is.
The bigger the issue, the longer it'll take him to make a decision of how he feels about it, especially if it involves making people unhappy. He stayed in an abusive relationship with his ex-wife for 8 years when he knew that he wanted out by year 2. He only just recently came to a final decision about a huge, huge problem within our circle of friends that came up a year ago. In each case, he went through every possibility, considered the opinions from each side of the situation, how he would deal with things if he had to make an unpopular decision, etc -- he went through every minute aspect of the situation thoroughly in his head. He had to be at peace with the idea that he was going to hurt people with his decision before he went through with it.
He tends to come to the right decision, but it takes time. If I try to make him make a snap decision about something fairly involved or important, he'll become very stressed and upset. He doesn't like feeling as though I'm putting him on the spot.
My ISFJ best friend is the same way. We've been talking about her moving to California and living with me for a years now, but even though she would love to and she knows she'll be happy out here with me, she's taking her time in making the choice to move out here because it means she'll have to leave her (worthless) family and (selfish) friends to start a new life. However badly they treat her and however unhappy they make her, she still has ties to them and she wants to make her exit as painless for everyone as possible, because having to deal with people being upset at her would be horrible.
I like to think of ISFJs as lovable little turtles.

I gotta have patience.