It's about couple that has broken up. The singer says their ex is now promiscuous because of the breakup, but they feel jealous when the singer gets close to someone else. The singer feels like the ex is a stranger because they lied to them and now they can't feel anything for them (the ex is also in 'disguise' possibly meaning that they live on lies, they're never true to themselves). The singer is slowly moving on (getting stronger every day), while the ex continues drowning deeper in promiscuity.
It's about couple that has broken up. The singer says their ex is now promiscuous because of the breakup, but they feel jealous when the singer gets close to someone else. The singer feels like the ex is a stranger because they lied to them and now they can't feel anything for them (the ex is also in 'disguise' possibly meaning that they live on lies, they're never true to themselves). The singer is slowly moving on (getting stronger every day), while the ex continues drowning deeper in promiscuity.