Travolta's marriage is helped a LOT by the fact that
A - he is the "main" star in it - while Travolta's wife is an actress - she is even less well known than Katie and their kids are not in the limelight like Suri is
B - his WIFE was in Scientology BEFORE he was and they were introduced by the church - they started out their relationship with both believing in Scientology
C - they do not live in CA/Los Angeles so their home /personal life is more private and less under scrutiny by the media/paparazzi
Also married a long time (by H-Wood standards) are Jada Pinkett Smith and Will Smith - Jada is a long-time public Scientologist - not so sure about Will - but he certainly appears to be fairly active and he and Jada are "public friends" of Katie and Tom. Again - with WILL being BY FAR the bigger star. IMO, the Scientology church seems to prefer MEN be the "big celebrity" in a marriage and if they are not, then the celebrity Scientology women are either married to a man who is less of a celebrity (if a celebrity at all) or not married - but regardless, has custody of any children. In fact, I think the Scientology Church uses members (like Lisa Marie Presley) to entice potential new male celebrity members (ask your self WHY Lisa Marie married both Nic Cage and Michael Jackson?) and why Tom Cruise And Katie suddenly became attached at the hip to Beckham and Posh (and to some degree JLo and Marc A).
You'll note that Conner Cruise is making his acting/movie debut in a Will Smith Movie...........
My Opinion