Is precum considered a relapse?

I think your last sentence is your answer. No one else can define your goals for you, but semen retention is a lifestyle choice that requires full committment, and it sounds like you realize that engaging in erotic fantasies is incompatible with the level of committment required.

Decide why you are practicing retention, and what other lifestyle changes will be needed to support that choice. Personally, I think that having unintentional emissions every other day indicates a deeper issue than perhaps you are admitting. Finding constructive, creative, non-sexual outlets for your energy when you "get horny" is probably your first place to begin. Sex fantasies are a substitute for porn, and whether you touch your genitals or not, you are engaging in those fantasies to a masturbatory degree. I don't know if you have decided on a reboot, or at what level, but it sounds like NO PMO with NO fantasy should be considered (based on a semen retention goal and your current out of control emissions). If you are just toying with semen retention because you read it has mystical health and virility properties (which there isn't much if any scientific evidence for), then maybe rethink that. You might also think about the ethical, psychological, and relationship problems inherent with using women you know as the objects of your horny fantasies. That's potentially a sign you may need a reboot more than you think.