Intravaginal ejaculation latency time and Coitus reservatus Sexual intercourse, when involving a male participant, often ends when the male has ejaculated, and thus the partner might not have time to reach orgasm. One possible reason for this distinct biological feature may be formation of strong emotional bonds between sexual partners important for social interactions and, in the case of humans, long-term partnership rather than immediate sexual reproduction. Sexuality in older age Typically, older men and women maintaining interest in sexual interest and activity could be therapeutic; it is a way of expressing their love and care for one another. Women with Intellectual disabilities ID are often presented with situations that prevent sexual intercourse. Female adolescents tended to engage in more sexual activity due to positive mood. It is a conditioned reflex of the pubococcygeus muscle, and is sometimes referred to as the PC muscle. The subsequent route of the sperm from the vault of the vagina is through the cervix and into the uterus , and then into the fallopian tubes. It has been linked to atypical levels of dopamine, a neurotransmitter. For example, the relationships can be ones of marriage, intimate partners , casual sex partners or anonymous. If there are more than two participants in the sex act, it may be referred to as group sex. Sexual arousal can also be experienced from foreplay and flirting, and from fetish or BDSM activities,   or other erotic activities. When a fertile ovum from the female is present in the fallopian tubes, the male gamete joins with the ovum, resulting in fertilization and the formation of a new embryo. It is related to the idea that opposition between two people can heighten sexual tension , attraction and interest.