neighbour eyeing wife

[indi_couples]

For the past few days, my neighbour is always eyeing my wife. Whenever he comes to our house, he tries to touch her on one execuse or other.
Is it ok or not?

It is her body and her desires. If she disliked it, she would have complained about it or even protested. So far she hasn't which means she likes it and is an active participant. In biological terms, she is a female in heat encouraging a potentially attractive male to make a move to inseminate her so that she can carry forward his superior genes. You are just a social construct who can at best slow down but not stop the inevitable mating that will happen. It's a question of thousands of years of social norms vs billions of years of evolution. 

The only way you can make yourself useful in this process is by encouraging her and possibly helping them during their mating.