Usually a mixture of deception and false promises. The honeymoon phase rolls in and uh oh, a few months later trouble in paradise. But you already committed to your partner and every relationship has problems, you'll tough it out and come out stronger on the other end. Few more months later you're so deep in denial and making excuses for your partner. If you quit now you'll be ridiculed for being naive and your partner will be upsed because he sucesfully gaslighted you into thinking his emotional baggage is your responsibility. Not to mention his or hers fanbase that'll rip you a new one, or atleast in the back of your mind it's a possibility.
This is the most scenario with e-celebs like cry or Lionmaker. But that house of cards falls 9/10 times.