"Further, the fact that the disputed properties were acquired during the couple’s cohabitation also does not help respondent. The rule that co-ownership applies to a man and a woman living exclusively with each other as husband and wife without the benefit of marriage, but are otherwise capacitated to marry each other, does not apply. In the instant case, respondent was still legally married to another when she and Jambrich lived together. In such an adulterous relationship, no co-ownership exists between the parties. It is necessary for each of the partners to prove his or her actual contribution to the acquisition of property in order to be able to lay claim to any portion of it. Presumptions of co-ownership and equal contribution do not apply."
G.R. No. 159310, February 24, 2009
CAMILO F. BORROMEO, Petitioner,
vs.
ANTONIETTA O. DESCALLAR, Respondent.
https://lawphil.net/judjuris/juri2009/feb2009/gr_159310_2009.html