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.
Make up fasting is considered obligatory fasting. Therefore, one should not invalidate it. Foreplay, in itself, does not invalidate fasting. What invalidates it is intercourse or ejaculation. If one knows that most probably neither of these will happen, then there is no harm in engaging in foreplay.
If the husband or wife know that fasting will certainly or most probably be invalidated due to any of these things, then foreplay is impermissible for them. It is impermissible for her to obey her husband if he demands this from her. Shaykh Ibn ‘Uthaymeen said: "It is impermissible for a man to engage in foreplay with his wife if he knows that this will lead him to ejaculate because some people ejaculate quickly. As soon as he begins foreplay with a woman or kisses her for example, or something of the like, he ejaculates. To this type of men we say: ‘You may not engage in foreplay with your wife as long as you fear ejaculation.’" [Majmoo’ Fataawa Ibn ‘Uthaymeen]
Allaah Knows best.