They Start To Get Tired And Sick A Lot
When you ask them to go out or to have sex they often give you excuses. If this happens once, twice or even three times or if your partner is really sick then it should not be a major concern but if this proceeds to happen over an extended period of time (weeks, sometimes even months) then you should become suspicious.
This sign is very common and is a pretty obvious one. When your partner is cheating on you and is no longer interested in you it is only natural that they will stop wanting to have sex with you.
You might try spicing things up a bit in your sex life or try and improve your looks in order to attract your partner’s attention. You might win them back. If you don’t succeed in that then your relationship is a lost cause.