Hailee Steinfeld feels "happy" when her partner is happy.

Hailee Steinfeld

Hailee Steinfeld

The 21-year-old singer-and-actress hasn't confirmed her relationship with Niall Horan - who she has been romantically linked with since February - but she admitted she loves the person she is when she's in a settled romance.

She said: "When you fall in love, you pick up on the tiniest things about yourself.

"You start doing things for this person and going out of your way to make them happy...

"I am one to spread [out] on the mattress and take up every inch of space. Now I don't want to do that anymore. I want to make as much room for you as possible.

"When you see them happy, it makes you happier. When you love who you are with that person... there's nothing that compares."

The 'Bumblebee' star insisted she's never been interested in wild parties and recalled how uncomfortable she felt at a bash some time ago.

She told the new issue of America's Cosmopolitan magazine: "That side of it has never been my thing.

"I got completely shut down by everyone and maybe it's because I didn't have a red Solo cup in my hands. I realised, 'I'm not going to stay here and feel uncomfortable just to fit in.' "

Hailee started her acting career when she was just 14 years old and though she's proud of her achievements, the 'Pitch Perfect' actress does regret that she's missed out on some normal teenage experiences.

She said: "I used to go on Facebook and see all my friends dressed up for winter formal or homecoming or prom. I would think, 'Even if it's the worst night, I'll never know what that feels like.' "