With mature heroes I mean above 30 years of age...
Suggestions welcome for every genre but the book should have at least some lovemaking scenes.

Nowdays it's very difficult find a romance like you describe, the writers have to be politically correct, maybe "Scusa ma ti chiamo amore" by Federico Moccia, (I think it is not translated into English) or "Ice" by Karen Marie Moning.
Maybe if you read the "classics romantic novels" (Johanna Lindsey, Shirlee Busbee, Jude Dereraux....) you can find more examples.

You should try "Heart shaped box" by Joe Hill. It's about an old guy who is a rock star.

You can see My New Step-Dad by Alexa Riley, wah... that book bring erotic to the new level and many books by Alexa Riley that the story about older man younger woman! And for my favorite book was Love, in English and Love, in Spanish by Karina Halle, but those 2 last books contains a topic that I really hate : Heroine are the other woman that make the hero's marriage collapse #HeavyTopics, but still, it was unusually great books.

Check out Irish Johansen, Carole Mortimer contemporaries...

You can try She's Too Young by Jessa Kane. The heroine is 17 and the hero is in his 30s. It's an erotic novella though. There's also a sequel.

You can try books by Sylvia Fox. They're have what you looking for