Hi Marina! It is referencing the malleable nature of a flip-flop which in this context connotes weakness. Therefore the actor is saying that he doesn't have a very strong will when it comes to finding a partner. Hope that makes sense!

We have a verb in English, "to flip-flop", which means to change your mind rapidly back and forth between different alternatives. I've never heard "I have the will of a flip-flop" - I guess it means something like "I can't stay committed to one idea or project because I don't have enough willpower". But it's a bit of an unusual way to express that idea.

No motivation

In this case I think what the author was trying to convey was that they are not very motivated. The reason is because a literal flip-flops shoe often breaks easily and it is always flopping around. So comparing this to the way the author feels could mean he is giving up or is unmotivated.

I've never seen that expression. He probably means he has no willpower; no determination. He changes a lot.