Even though younger generations are more sexually active compared to how things were in the past, there should be no problem if 2 teens decide to engage in sexual intercourse.
The problem comes when an adult, with a lot more experience and knowledge in life decides to have a relationship with such a young person. This could be risky because the adult can be capable of manipulating the young person into doing certain things that are not good for him/her.
Science actually says otherwise that a lot of problems are associated with teenage's sex, be it with fellow teenagers or adults.
Now that we live in the time era of incels and perma-virgins, sometimes these teenage girls come out ahead in a relationship with an older boyfriend than with some punk their own age who only wants to get inside her pants. I don't know what the situation is in Nigeria, but the United States of America has a severe epidemic of deadbeat teenage fathers.