Is hiring a Private eye going too far?

I’ve been having some issues w/ my ex-girlfriend, who i am still ‘dating’. I am trying to get back together with her and she says she needs time and she has lost a lot of interest in sex. She doesn’t answer my phone calls a lot of the time any more, or texts me back for days at a time (sometimes). But she always says give her time.

I have a very strong feeling she is seeing somebody else and my confrontations about it she assures me she isn’t dating anybody. And I cannot trust her.

I’m considering hiring a private eye to tail her for a few nights. Just to see if I can trust her… I’m worried that if doing this, will I permanently destroy the relationship despite what he finds? If she’s clean, I’m going to have to hide this from her and that can’t be good. If shes seeing somebody else, well we know how that one goes. Does this go beyond the steps of decent ethics and morality? not quite sure what to do…

I got a price quote and everything… just gotta pull the trigger (Quite an expensive endeavor to get into…. but I must know)