Republic Act (RA) No. 9262, otherwise known as the Anti-Violence Against Women and their Children law of 2004 makes cheating on your wife a crime. Sec. 3(c) states that psychological violence refers to acts or omissions causing or likely to cause mental or emotional suffering of the victim such as but not limited to marital infidelity.
As a crime, cheating on your wife carries the twin penalties of imprisonment and monetary fine.
Note also that RA No. 9262 is aimed at protecting the dignity of women and children. As such, the act of violence, to constitute a crime under this special law, can be committed by any person (girl or dude) against a woman who is a wife, former wife, or against a woman with whom the offender has or had a sexual or dating relationship.
Not to downplay the evils of physical violence (in legal speak: causing physical harm to women or her child or merely threatening to do that), women are given a quick remedy under RA No. 9262. Under section 14, women can ask for a Barangay Protection Order (BPO) from the Punong Barangay who shall issue the BPO. If the Punong Barangay is unavailable, women can file the apllication with any available Barangay Kagawad. Note that these barangay officials are mandated to issue the BPO on the date of the application, ladies. This is an urgent matter involving life and limb so the law naturally wants to expedite the issuance of a BPO.
How will the BPO protect me?
The BPO will be enforced by law enforcement i.e. the police. The BPO may, among others, order the removal of the offending guy from the residence (even if the guy owns it). The BPO has a life of 15 days.
For more permanent remedies, I suggest reading the full text of the law and its implementing rules at http://www.pcw.gov.ph/sites/default/files/documents/resources/ra_9262_and_irr.pdf
20 something lawyer