All perfect praise be to Allaah, the Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Foreplay without discharging semen (or ejaculatory fluid) does not require Ghusl. Ghusl is due only (from both parties) when one enters the tip of his glans (the head of his penis) into his wife's vagina or when semen (or ejaculatory fluid) is discharged. Mere foreplay does not require Ghusl.
Moreover, Ghusl is not a prerequisite for valid fasting. The person who is in a state of Janaabah (ritual impurity), nonetheless has a valid fast. Nevertheless, he is required to make Ghusl to perform the prayers because prayer is invalid when one performs it while he is in a state of Janaabah.