Chazal tell us that the sea split in the merit of Yosef Hatzadik. What is the connection between running away from zenus and klal yisroel meriting to go through, why should one have a bearing on the other?
I think a possible explanation is that klal yisroel were in danger at that time, as chazal say - in shomayim the angels were asking, "what is the difference, they both serve avoidah zarah, they'll never serve You, their alleigance is elsewhere, just like the Egyptians."
Yosef Hatzadik is example of the potential within each and every Jew - he was able to live with the Egyptians all by himself, as a teenager (no support, no yeshiva, no family, no nothing, all the temptation day in, day out) - and against all odds, he was able to hold firm in his allegiance to Hashem.
Hashem was able to answer the melochim, "no - they're different, look at the potential within them - look what an 18-year-old Jewish boy was able to do against all the odds." His example of what a Jew can do killed the debate. They merited to be saved!
(If what I'm suggesting is true), the lesson here is that we have the potential of Yosef HaTzadik within all of us. Presumably, we are being compared to the 'mitzrayim of our day - the western culture' whilst we are steeped in our addiction - "look, they are no better than the non-Jews!" - but we, too, are capable of running away from the shmutz and then, with Hashem on our side, we will be zoiche to our own kriyas yam suf and get to recovery on the other side!