3. Mentioning Ex
If your partner talks a lot about their Ex, you should be suspicious that they are not over their ex yet and you might just be a rebound. It is even worse if they compare you to them. This should be a clear sign that their heart (and head as well) are stuck with their ex and this current relationship with you might just be serving as a distraction. This might just be an ego-boosting thing after their failure in their past relationship. Also, be wary if they avoid making eye contact with you.