The couple have only been dating for three months but pals of the `How I Met Your Mother` actor say he has never felt this way before.

A source told People magazine: "Jason is totally smitten. It`s like the first girl he`s ever been this way with."

The insider added that Michelle - who has a six-year-old daughter Matilda from her relationship with the late Heath Ledger - "hasn`t been this happy in forever".

Recently, the pair enjoyed a "lovey-dovey" date as they spent a romantic evening watching James Corden`s `One Man, Two Guvnors` Broadway show at the Music Box Theatre on West 45th Street, New York.

An audience member said: "They look very lovey-dovey. She looks so pretty in white, and he`s in a suit."

Previously, the blonde beauty was seen leaning in and kissing Jason on the cheek and rubbing his back at the after-party of the premiere of his latest movie `The Five Year Engagement` in April.

The 32-year-old actor was also spotted holding the 31-year-old star`s hand and whispering in her ear at the New York event.

Michelle and Jason have been friends for years after meeting through her friend and his `Freaks and Geeks` co-star Busy Philipps.
sections: Celebrities