Tips and tricks to find out if your partner is lying

So it happens that you dating and when you dating and you feel like your partner is not being honest with you what tricks and tips should you take to find out the Truth fistly never go through his/her phone all got to do is to play it cool and let him/her borrow you his phone then from the you can access all the information you want and save certain contacts to your phone after that confront him/her with questions bare in mind you already know the truth so that gives a little chance /room for lying and always be on the lookout for certain compliments from the opposite sex or places he/she goes to on a regular without you