Tim has never had a problem asking for advice when he needs help.
So that's not the problem.
The problem is finding someone to ask.
He's scoured his own mind to try and remember how his last real relationship went, but he was still in grad school the last time he had a girlfriend for more than a year, and the man he is now is so much different from the boy he was then, that it doesn't seem to be a good comparison.
Sooo... who to talk to?
Gibbs is good at helping you see straight, in that silent, you sit next to him, drink some, and epiphanies hit sort of way, but Gibbs has also been divorced a million times, and the closest thing Abby has to a dad. Plus, if he's trying to keep this quiet to avoid getting tripped up on Rule Number 12, talking to Gibbs about it isn't a brilliant plan. So, he's out.
Ducky—who, Tim is secretly afraid of turning into, the man with the thousand stories and no one at home to tell them to—may have a tale for everything, but has even less practical experience on this than he has. And, while he's sure Ducky will have many fascinating bon mots on the subject, he's also sure that he'd like to talk to someone with a clue as to how to keep a long-running relationship going.
He could talk to his grandmother, but, well, ewwww... Penelope's more likely to want to talk him through the intricacies of the Kama Sutra than help him get into a good headspace for a real relationship. Plus, even if he could get her off of sex, and onto relationshiping? relating? whatever, she'd likely tell him something like stop thinking so much and just do it. Not advice he wants to hear, let alone advice he'd know how to act on.
The idea of Tony enters his mind, and then does an abrupt about face and marches right back out again. Getting advice from a guy whose A: Last successful long-term relationship was an undercover mission. B: Made out with his ex-fiancee back around Valentine's Day, while C: In love with his partner, while D: Being completely unwilling to admit that he is in love with said partner, does not in any way strike Tim as a good idea. Add in the fact that Tony can't keep a hot bit of scuttlebutt to himself, and talking to Tony is a disaster waiting to happen.
Thinking of Tony makes him think of Ziva, who has the advantage of being able to keep a secret, and on top of that, is a woman, so she might have a better idea of what it's like to be the female half of the equation than Gibbs or Tony, but Ziva has the worst relationship track record he can think of. Sure Gibbs might not be a huge fan of his ex-wives, but unlike Ziva's exes, they aren't responsible for killing anyone, or trying to kill anyone, like, you know, Tony.
It takes him two full days to figure out that he does know someone to talk to. Someone his age. Someone who is married (barely). Someone who loves Abby, knows her well, and would be willing to keep a secret if said secret would work out well for her.
It's time to talk to Palmer.