(Cover) - EN Showbiz - Justin Timberlake is reportedly struggling to come to terms with the end of his relationship with Jessica Biel, as he was so invested in their future.

The couple confirmed they had gone their separate ways last week, after around four years of dating. Neither has discussed the reason for the split, but it was widely reported the romance was on the rocks for some time.

There has been intense speculation about who called time on the relationship, with the official line being that it was a mutual decision. Justin is said to be devastated by the break-up, and doesnt know how he is going to fill his time now hes single.

[He] is upset. They always spent vacations together. They always spent down time together. He was invested in her, in her friends and family, a pal of Justins told People.

He was invested in their relationship on a lot of different levels. After four years it's just not easy to walk away from it.

Throughout their romance there were rumours Jessica was keen to tie the knot, and it was even said that Justin had been spotted ring shopping. The speculation has been dismissed by the insider, who insists Jessica never pushed Justin into anything.

The topic of marriage wasn't the catalyst or final straw that broke up the relationship, the friend added. There was no ring shopping. She wasn't even thinking about marriage. That didn't play a part in their break-up at all. (C) Cover Media