He might slowly start texting other women. You have a feeling he's been talking with someone else a lot. Maybe there's a new coworker or an old ex. And it's not that he's cheating, it's just some guys have an escape plan of sorts.
Catalog
Frank
He's never happy around you. He stops joking around with you. He doesn't laugh when you try and mess around with him, or drop one of your inside jokes. He just seems like he's... there.
He stops confiding in you. You wind up hearing about his promotion from a friend, because you're not the first person he wants to call anymore when something major happens.
Squeeze the base of his penis. Think of it like bending a hose in half to stop the flow of water, but definitely do not bend his penis in half under any circumstances. Just give it a firm grip.
New positions and sensations will distract him and make him last longer.
Have him masturbate beforehand. Ejaculating an hour or two beforehand makes it harder for a man to come quickly.