I’m a little confused – is it a triangle between two pregnant women and one man who looks like a famous actor?

Interesting! (If I’ve got it right, of course). The doppelganger characteristic seems to imply that he may be shallow, relying on his looks and its similarity to someone famous to live the high life without actually earning anything. In which case, a good flaw – and one he would need to overcome if he is to make things right with the two women he loves.

Can I suggest:

“A man who coasts through life by virtue of looking exactly like a famous actor impregnates both his wife and his girlfriend at the same time, and sets out to convince them to share a home together”