well that might be his thing. he might like it like that or just does it unconsciously. my bf does it when he is really horny or really enjoying himself. best thing to do is to talk to him about it.

Why worry or analyze??
What does it matter in the overall scheme of things?

That the two of you find pleasure in each other's company and enjoyment in your activities is all that should matter.

Some guys may remain still, others may tense their body, someone else may react to the intense buildup by elevating his hips or pelvis; others may thrust in reponse to the buildup. What does it matter who does what, when?

Well, Doc, from the female side of things, it can really matter. Heavy or rapid thrusting can present a real challenge to the one performing fellatio. Until I am comfortable with a partner's habits, I am very careful what positions in which I do oral.

Women need to know how to protect themselves from a penis being rammed a bit too far. I am always in a postion with one hand to stop "over-penetration." I am also aware that most men, in my vagina, thrust deeply and hold relatively still during the actual ejaculation. As they approach ejaculation in my mouth, I stretch them downward towards their bodies and hold still with constant suction. This replicates what appears to be the desire doing coitus.

Creative use of the hands can give the man a greater feeling of depth and proper use of the tongue can heighten sensitivity. While beginning women have concern over the taste, force and consistency of the ejaculate, unexpected or extreme thrusting can be a real threat.