Some drawbacks of sexual reproduction are:
1. It needs cooperation between mating partners and delays the start of each reproductive cycle.
2. It increases the energy needed for reproductive processes and lowers the strength organisms can maintain.
3. It slows the development from fertilization to birth and limits the total offspring released in a season.
4. It relies on partners being ready at the same time and increases the risk that mating attempts fail.
5. It requires animals to spend longer outside protected areas during mating and raises the danger of predator attacks.
Check it out related article on advantages and disadvantages of sexual reproduction.