"If we don't fix our sex life, our marriage will end".
Nope. There is a huge difference, and you changed my words. The first is accurate. The second was this:
"**I** will not live forever in a sexless marriage."
YOU may hear the implication, but you are not demanding anything of the other person. You are just merely stating what YOU will or will not do. If another choses to go the sexless route... fine, no judgement... you leave for YOU (and who you have defined yourself as), not to PUNISH them.
In the aforeseaid example, an if/then statement is a definite threat of consequential action, meant to punish or instruct.
