Logic?

Im a white guy attracted to black women. A coworker told me i know you're attracted to black women. Don't tell them you're a Trump supporter or Republican. 

This coworker is likely operating on two stereotypes: That black women are Democrats and that Democrats will not date Trump supporters.

According to data from last year, among black women who are registered to vote do lean more heavily towards the Democratic party than any other demographic: About 85% are Democrats and 10% are Republicans. And, according to a Pew Research survey from 2020, roughly 70% of Democratic voters on the dating scene said they would probably not or definitely not date a Trump voter. So, in both cases, the stereotype is true about the majority, but not about the whole group. Within those numbers, there are some important variables like age that aren't accounted for, but if you assume an even distribution that would mean that about 60% of black women wouldn't date Trump supporter. Definitely reduces your pool of potential partners, but not insurmountable odds.

Anecdotally, I was on the dating scene during the George W Bush and Obama administrations, during which time my political views shifted from conservative to centrist. I have noticed that the reactions of liberal women towards men who support Trump is a lot more visceral than they were towards men who supported previous Republican presidents and candidates. And not without reason, Trump has a history of making comments they consider mysoginist, was instrumental in the overturning of Roe v Wade, and has faced a large number of accusations of sexual assault and misconduct, one of which he was found liable for in court and others he seemingly admitted to. They basically feel that the fact that a man would continue to support Trump in spite of this, and that many men who support Trump just brush these things off and don't seem concerned by them, is a sign that these men don't really care about women's well-being.

That said, there is one more layer to this. Is it really a good idea to date someone if you need to hide your political views in order to do so? Consider the effort and stress that would go into hiding that from someone you're dating for an extended period of time. Then, you have a couple of possible outcomes: Either you manage to hide it for the duration of the relationship, your views come out later and she accepts them, or your views come out later and she considers your views, and/or the fact that you hid them from her, to be so negative that your relationship either gets damaged or ends as a result.

The statement from your coworker carries several implications and potential logical fallacies:

1. **Hasty Generalization**: Your coworker seems to be making a generalization about how all black women might react to someone being a Trump supporter or a Republican. This is an example of a hasty generalization fallacy, as it assumes that all individuals within a group think and react in the same way without considering individual differences.

2. **Stereotyping**: The statement relies on a stereotype that all black women share the same political views or are uniformly opposed to Trump supporters or Republicans. This ignores the diversity of opinions and beliefs within any racial or ethnic group.

3. **False Causation**: The statement implies a cause-and-effect relationship between being a Trump supporter/Republican and the potential for romantic interest from black women, suggesting that political affiliation will directly lead to social repercussions. This oversimplifies the complexities of personal relationships and attractions, which are influenced by a multitude of factors beyond political alignment.

4. **Assumption of Homogeneity**: The coworker seems to assume homogeneity among black women regarding political preferences. This dismisses personal agency and the fact that political opinions are deeply personal and varied.

5. **Black-and-White Thinking**: The coworker's advice implies a black-and-white view of political affiliations and social dynamics, where one must either hide their political identity or face negative consequences, neglecting the nuances and potential for open dialogue and understanding between individuals with differing views.

In summary, it's important to approach such scenarios with nuance and recognize that individuals have diverse perspectives and shouldn't be boxed into monolithic categories based on race or political affiliation. Open communication and genuine interactions are more constructive approaches in personal relationships.

No fallacy. It's merely an opinion and probably well-intentioned advice. Rather than a hasty generalization or ad hominem guilt by association the friend has reasonably ascertained that there is a high probability that the girls you're interested in might not appreciate extreme political leanings. 

Trump Is a self obviated racist. He was even sued by the government for discriminating against Black Americans. 

I'm a man attracted to all good-looking women, regardless of race. So, I don't understand being attracted to only black women. However, do not continue the discussion at the hierarchical level you state here.

"Don't tell them you're a Trump supporter or Republican" conclusion is based upon something, and you don't know what it is. Therefore, drop down the ladder and ask: "Why?" That is where you will begin to peel the onion skin.