You're dating a really terrific guy; your relationship is wonderful in every way -- except you can't help but question if he's 100 percent over his ex. Can you trust your instincts on this one? Check out these warning signs which indicate that maybe, just maybe, he is still pining for his former flame.

He's still in close contact with her

It's not unusual for people to keep in touch with their exes, especially if there are kids involved. But if they're calling, texting, emailing, Tweeting or commenting on each other's Facebook photos on a regular basis, watch out. And be very wary if your beau's acting secretive -- hiding messages, taking the phone into another room or lying to you about the contact. Your suspicions are probably warranted.

He's stalking her online

If he's obsessively checking on her Facebook status or following her Tweets to see what she's up to, she's still very much on his mind. "You guys may have a great relationship, but if he's not really over his last love, you can bet that the moment she hints that she wants him back, he'll be at her feet," warns Natasha Burton, author of The Little Black Book of Big Red Flags.

He can never say no when she asks for help

His former girlfriend still calls on him for all sorts of favors -- from helping out with her flat tyre to fixing a leaky tap to borrowing his GPS -- and he always obliges. Sure, he might just be one of those super-nice guys who can't say no. Or it could mean that there's something more. Gently tell him how you feel about his spending time with an ex. If he really loves you, he'll put your needs over hers. But if he continues to be at her beck and call at the risk of upsetting you, clearly, he still has feelings for her. It's time to move on.

He still talks about her

It doesn't matter whether he's singing praises or speaking about her in a negative way, the reason why a guy talks about an ex is because he's still thinking about her. "If he still gushes about her or he can't hear her name without getting angry, watch out: He obviously has some strong feelings left for her, which will leave a sticky residue on your relationship," says Burton.

He still holds on to mementos from his past relationship

Not a big deal if he's still got photos of his ex-girlfriend or some remnant souvenirs stuck in a box somewhere in storage, dusty and forgotten. But if you catch him checking out those old photos a lot or poring over gifts and keepsakes from her, it's obvious he hasn't got over his grieving.

He's unhappy she's dating someone new

If your guy is upset or annoyed that his ex has found a new boyfriend, it's a definite red flag that he hasn't completely let go of her. Remind him that he's in a new relationship -- with you -- and there's no reason her love life should be any concern of his.