It seems that Prince Harry is really getting serious with current love interest, Cressida Bonas, as he is reportedly asking sister-in-law Kate Middleton for some relationship advice.

Just recently, the preggy duchess and the 24-year-old socialite have been rumored to be at war, apparently because Cressida's elder sister, Isabella Cathrope, had been competing with Kate for Prince William's attention in the past.

However, sources have dismissed the reports, revealing that the soon-to-be-mom Kate is happily giving brother-in-law Harry tips on how to make his relationship last.

Prince Harry has been reportedly telling his friends that he is in it for the long run and he's ready to settle down with Cressida and doesn't want to ruin things between them.

A source from The National Enquirer claimed, "Harry's so head-over-heels in love with Cressida, that with Prince William's approval, he's enlisted Kate's help to make sure he doesn't sabotage the relationship."

The insider also adds that Harry has told Kate that "he really respects her opinion and guidance, and he's relying on her for advice because Cressida is the woman he wants to spend the rest of his life with."

Amid the rumors, the 31-year-old Duchess of Cambridge wishes Harry to settle down happily with Bonas.

The National Enquirer insider shared, "Kate, who wants nothing more than to see her rowdy brother-in-law settled down, sat with Harry and counselled him on the do's and don'ts of building a great relationship."

"She told him don't drink too much--and none of your filthy jokes! Be attentive, never talk about ex-girlfriends and don't put yourself in any more situations that are embarrassing to you and everyone around you!" the insider added further.

It was also said that 28-year-old prince is quite fearful of sabotaging his relationship with Cressida, that's why he seeks the duchess' opinion.

"It's obvious Cressida has won his heart --so we're all hoping that he doesn't mess things up. Even William's amazed at his new found maturity in realising he has found the right girl--and desperately wants to do the right thing and make it work."

Do we hear the sound of wedding bells in the making?