Just be aware that he may not feel like going then either but try to get him there. This is a great program but it isn't a guarantee. Sara made a great point - it can't help if you don't go.
It didn't do a lot for us because my wife was heavily involved in an EA when we went and I have since learned through getting access to phone records that the A never skipped a beat while we attended the weekend and post sessions. In fact - it intensified partly due to the fact that the OM stepped up his pursuit during that time from what I can tell.
Therefore there can be things outside of your control, but if both partners have an open mind it can work wonders which you will hear from the presenting couples when they talk about their situations.
Learning how to communicate better is a big lesson you take away, and they also effectively get the point home about how a marraige is something to be cherished and not thrown out the window just because things aren't going well.
ME/XW:47 S21, D19, S15, S14 M:21 T:26 W moved 6/10 I filed 7/10 D final 4/12 remarried 8/12 W wants to R 12/10 and 4/11 but I decline