Angels third season led to quite a character change for Wesley; the result divided fans of the show. Personally I felt the character became too serious, but there is no denying that it had a hell of an impact. Wesley had often been a source of comedy for the series but the birth of Angels son changed things. It led Wesley to make a decision which had devastating consequences.
The birth of Connor-though alarming- is a joyous occasion for Angels crew who all enjoy doting on the miracle baby. That is until Wesley discovers a prophecy which says Angel is destined to kill the child. Wesley keeps the prophecy from everyone and decided to take Connor from Angel. This grave error in judgement not only leaves him badly injured, but also condemned Connor to a hell dimension.
Angels reaction is upsetting but justified. Connor was always likely to have a dangerous life; but to be made to suffer by the hands of a friend is something Angel never could have anticipated. Wesley was trying to do the right thing by the child but his actions ruined the lives of his Angel and his son.