Emotional cheating- it's not something which is easy to decide( not my words, Google's) some of the points that I read are: if you share some big news with someone other than your partner.
: sharing your big concerns/ worries with someone other than your partner
: showing sign of puppy love for someone else
: messaging someone else and lying about it
: having inappropriate thoughts about someone else
: making your partner placeholder
: deleting calls or texts
: putting someone else before your partner
: complaining about your partner with someone else
Even these things can differ from relationship to relationship. Every relationship has it's own criteria of emotional cheating; be it marriage or engagement, living relationship whatever.