Hilary Duff's estranged husband hoped she would call off their divorce.

MIKE COMRIE, who separated from the blonde beauty in early 2014, was reportedly ''caught off guard'' when the 'All About You' hitmaker filed court documents seeking to end their marriage and primary custody of their three-year-old son, Luca, in February.

The former ice hockey player is said not to have signed the documents until April because he was ''hoping to reconcile.''

A source close to Mike, who is preparing to fight for joint custody, told US OK! magazine: ''They had discussed sharing custody in the past, so he was really caught off guard. He waited until April to file because he was hoping to reconcile, but when he realised that's not happening he decided to fight back.''

The 27-year-old star allegedly decided to pull the plug on their marriage for good after reports claimed Mike was drunkenly hitting on other women in a bar in Los Angeles earlier this year.

Hilary allegedly doesn't think her estranged husband is ''really up for being the kind of full-time dad you need to be with joint custody.''

Another insider added: ''Hilary was really betting that Mike wouldn't fight this decision, but she was wrong.

''It's sad that their relationship has come to this, but Hilary is prepared to tell the court everything she knows in order to get custody. If Mike wants a battle, he might not walk away looking like the good guy.''