This one's a pretty good indicator of a relationship about to go downhill. If you suddenly feel like you just can’t do anything right and your girlfriend seems to be habitually pointing out every flaw in your life, personality and relationship, it’s probably indicative of her waning interest in you.
If she is in fact cheating, it's likely her guilt is causing her to justify her own behaviour by pointing out your flaws--so don't take it personally!
If you notice a sudden shift in her priorities, perhaps it is time for you to consider the facts more prudently. If she really is involved with someone else (physically or emotionally), chances are that she will suddenly start spending a lot less time with you.
To add to that, she'll probably start valuing your time a lot less. So watch out for last minute cancellations, a sudden increase in late hours at work, and a general disregard for activities that you want to do together.
Sapped Sex Life
While there could be other reasons for this, a newfound lack of interest in sex with you is a pretty good indicator that she's deriving some other sorts of sexual satisfaction.
On another, much more disturbing note, if her mind appears to be elsewhere (read: on someone else) even while you’re at, it you really need to have an open-minded conversation with her and establish the truth once and for and all. This also tends to be the most common way men figure out their partners are cheating on them.
A new haircut, new clothes and a sexy new attitude is a definite indication of her being en route to upgrading her life.
Now it may just be that she's just on the road to self-improvement, but it's also possible that she's trying to impress a new man in her life. Whichever it is, tread carefully!
Mysterious New Man
Nothing speaks volumes about a cheating lover quite like the sudden and unwelcome appearance of a ‘mystery man’ in their life. It’s a tell tale sign if ever there was one but getting unnecessarily possessive without reason is also not justified.
Whatever her claim is about this man, from being a childhood friend to a girlfriend’s cousin trust your instincts and check whether anything is fishy. Is she refusing to let you meet him or acting strange when you ask her about him? If so, perhaps you have a reason to get slightly suspicious.