This is a pattern of Bishopening.Your opponent made an inaccurating move
soonly@3.Mf3?!...However,u didnt take it as a chance2develop.And now,in reverse,u're beeing threaten by the attack of knight on weaking square f7.
The only way is 4...d5>Te7>0-0...Gl in game !
I'm comforatable playing when im white, but when im black this seems to happen alot...