Source: Being a pseudo-parent to Britney Spears 'exhausting' for Jason Trawick

Britney Spears and her agent fiancé Jason Trawick may have just officially announced their separation on Friday, but according to a source close to the couple, things have been pretty much off for a few months now, and Trawick was the main one to let loose the ties.

"It has really been in motion awhile. Jason has been very stressed and concerned for Britney and what she might do if he left," an insider told FOX411's Pop Tarts column. "He is worried about her and really loved her, but it started to take a real toll on him. The burden of taking care instead of a partnership where she also takes care."

Spears hit headlines across the world beginning in 2007 in what seemed to be a breakdown before the public's eyes - shaving her head, partying pantyless, beating paps with an umbrella and an eventual psychiatric hold at a Los Angeles hospital. The meltdown prompted Spears's father, Jamie, to take out a  conservatorship over his daughter - which she remains under. Last April Trawick too came on-board as co-conservator. However, it seems agreeing to take on such a responsibility over a romantic partner proved fatal to their relationship.

"Jason took on the role of 'parent' and Britney the role of 'child' when he agreed to conservatorship. This makes an uneven balance of power, typically kills intimacy and creates a dynamic of conflict in the relationship," explained licensed psychotherapist, Stacy Kaiser. "Britney, due to her past mental health issues probably requires a great deal of walking on egg shells to keep her balanced. Anyone close to her would be afraid of triggering an episode like we have seen in the past. As great as Britney may be, any person needing to live under such a need to be cautious and worried would struggle."

But in breaking off their one-year engagement and four-year courtship, Trawick has also relinquished his co-conservator role. Superior Court Judge Reva Goetz received Jason Trawick's resignation Friday and removed him from the conservatorship proceedings.

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"It was exhausting for Jason and not the way he wanted to live his life," continued the source. "But this is best for both of them."

We're also told that Trawick worked to assemble a supportive team to help the pop princess personally and professionally in the lead-up to his exit, which included last week leaving her agency William Morris Endeavor (WME) and signing with Creative Artists Agency (CAA) in all areas worldwide.

The mega-star also notified Fox this week that she was leaving her judging role on "The X Factor."

Trawick was and remains well-liked in Spears tight-knit team of family and confidantes, with many believing he was a positive influence on Britney and her two young boys. However, the "Toxic" performer apparently took a little more convincing - with another source close to the star telling us that at least initially, it was her parents really pushing the relationship and hoping it would work.

A statement from the Spears camp confirming the break-up on Friday noted that the "difficult decision" was mutual.

"Jason and I have decided to call off our engagement. I'll always adore him and we will remain great friends," while Trawick added that he will "love and cherish her and her boys and we will be close forever."