Dreaming of making love with a stranger or stranger in love with you is very common. Majority of the time it has no meaning. This is because the dream is the result of some activity during day or constant thinking of love making, sex or romance. But if the dream happens naturally without any influence of daytime activity then it should be taken seriously.
A single person dreaming of stranger in love with you or making love with a stranger means that you are going to face emotional problems and relationship issues. Someone whom you trusted might cheat on you.
A married person seeing the dream means you are going to cheat your spouse or your spouse is cheating on you.
As told earlier, such dream usually has no meaning as majority of time it is due to some intense activity based on the subject during daytime.