The ex boyfriend gets mad as he has to come to terms with the strong possibility that his ex girlfriend has moved on from him emotionally.

By being on a dating site, the ex girlfriend would be indicating that she is looking to find a new boyfriend or even hook up with someone.

The ex boyfriend doesn’t like this outcome.

Though he may be the ex boyfriend, he may still feel territorial when it comes to his ex girlfriend.

That sense of possession doesn’t go away simply because he is no longer in a relationship with her.

He may have still felt a sense of ownership over his ex girlfriend even though they were no longer in a relationship.

In discovering that she was on a dating site, he gets mad because it makes him feel insignificant.

He may feel a loss of control because of this.

As an ex boyfriend, he may have been hoping that his ex girlfriend would be unhappy over the fact that they were no longer in a relationship.

This may have been what he was holding onto after the breakup.

In making himself believe that his ex girlfriend is probably unhappy over the breakup and misses him, it may have allowed him to be able to handle the breakup a little better.

This may have made him believe that he meant a lot to his ex girlfriend.

This thought alone may have been enough to help him try not to take the breakup so badly.

However, upon finding out that his ex girlfriend was on a dating site, he gets mad because he may feel as though she felt no sense of tragedy or emotional pain over the breakup.

He may look at the fact that she was on a dating site as a sign that she may have never even cared about him at all.

This is especially true if he took the breakup really hard.

He may have had a really difficult time dealing with it.

He may have been consumed with thoughts about what led to the breakup.

He may have replayed the heartbreaking moment of the breakup in his mind again and again.

After going through all of this as an ex boyfriend, he gets mad when he finds out that his ex girlfriend was on a dating site because he would question whether she ever loved him at all.

If it was this easy for her to get on a dating site after the breakup, she must have been faking it when she acted as though she loved him during the relationship.

Hence, the ex boyfriend would feel a sense of betrayal.

He would feel as though his ex girlfriend misled him.

He may have taken the breakup so hard that the thought of joining a dating site never even crossed his mind. However, his ex girlfriend didn’t seem to have a problem with joining a dating site.

An ex boyfriend who has experienced this kind of emotionally tumultuous aftermath to a breakup would hope that his ex girlfriend would have experienced the same.

However, in finding out that she was on a dating site, he feels like he was the only one who was suffering as a result of the breakup.

It makes him question just about everything that his ex girlfriend told him during the relationship.

It makes him wonder if anything that his ex girlfriend told him about how she felt about him during the relationship was even true.

He is mad at the possibility that the entire duration of that relationship was a farce.