Honestly, a guy's thinking would be to decide to straight up tell her that it's over. Pero decision is different than action. Easier said than done to tell a woman straight na it's over lalo na if may pinagsamahan talaga kayo.
So for me, mas importante na maging faithful ka hanggang sa official na tapos ang relationship. Karamihan kasi ng mga lalaki, nag sstart na mamansin ng ibang babae the moment na na ffall out of love sila. It ain't over till it's over. Build the courage to tell her directly what you feel (kahit gano kahirap), wag ka lang gago.