IRL, I don't believe in marriage...if you love somebody, putting a binding contract only cheaps the relationship. That being said, I plan to not get into romance/intimacy till 70+.
But it's true...when doing an assassin RP, if they are a band that is close and trust each other, they trust the leader to be able to bust themselves out. In fact, the whole getting captured thing would have been a plot by the leader in order to kill a person they could only get to by being captured.
Of course, and assassin's guild is mainly something that has a lot of internal power-playing, no doubt there would be one or two people in the guild who'd take this opportunity to climb to the top.
This is more or less a band of mercenaries who specialise in assassin like skills, which isn't crazy uncommon in the scheme of RPing, if you think about it.
We shoulda hashed this out before the start of the RP.