Alex Rodriguez and Jennifer Lopez. Picture: Reuters

Jennifer Lopez was shocked when Alex Rodriguez proposed to her at the weekend.

The retired baseball star got down on one knee to pop the question to the 'Jenny From the Block' hitmaker over the weekend during a romantic vacation in the Bahamas and though they are very happy together, the 49-year-old singer-and-actress wasn't expecting to get engaged.

A source told People magazine: "Jennifer is ecstatic and so are their families and friends. Very few people knew Alex planned on proposing. 

"It was very much a surprise for Jennifer. It was just how Alex wanted it."

The 'Shades of Blue' actress - who has twins Max and Emme, 11, with third ex-husband Marc Anthony - is the "happiest she has ever been" with 43-year-old Alex, and their friends think they are true "soulmates".

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she said yes ♥️

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The source said: "They are incredible together. Very much soulmates that bring out the best in each other and are so supportive of each other.

"From the start, they moved very quickly. Their relationship was always very passionate. Jennifer quickly fell very hard for Alex. And she quickly started planning for the future."

According to the insider, Jennifer and Alex - who has daughters Natasha, 14, and Ella, 10, with ex-wife Cynthia Scurtis - had discussed getting married "from early on" in their relationship but the 'On the Floor' singer "realised that she wanted to live more in the moment" and "enjoy what they have together with the kids".

Alex's proposal came just a month after Jennifer insisted she didn't need to get married right now.

She said: "Among our children and work and all the wonderful things that happen, we are really living our best years. 

"We are grateful for this and we do not need anything else at the moment. We have to do things at our own pace."