Why Giving good head is actually an evolutionary disadvantage

According to natural selection and darwinism an individual of a species is more likely to live longer due to having more helpful traits based on genetic mutations, this helps spread these mutations to their offspring. Now let us bring in what is now commonly known as "head" or a "blowjob" into the equation, since the reproduction of offspring requires semen to enter the females fallopian tubes, giving head may prevent this from happening. But say what would it matter if somebody gave head and still followed through with natural reproduction (semen meeting the fallopian tubes), well more likely than not it is statistically inevitable that those giving better head would cause higher rates of "purposeful" or "accidental" ejaculation during their proccesses. Those who do not give head or are worse at it are statistically more likely to recieve higher rates of semen meeting their fallopian tube, therefor creating more offspring in the population.

Conclusion: Eventually "blowjobs" may fizzle out with evolution or simply we may evolve out of it, you never know if you are the last generation in the evolutionary tree of our species to get good head...