Most Helpful Guy
This is often caused by circumstance, and how quickly you offer it.
If you are constantly meeting guys at bars, parties, pubs, clubs etc. then you are decreasing your chances at finding someone long term.
Usually, people looking to meet someone in those environments want one thing. Especially after a few drinks. This applies to both guys and girls.
Also, if you meet a guy, go out for dinner or a movie, and let him in (in the physical sense), he may just see it as a "that was easy" situation. There is nothing wrong with this, as girls and guys need sexual fulfilment without the baggage sometimes.
However, if he gets an impression that he can have you sexually whenever he wants you may find yourself in 'booty call', or 'benefits' territory.
Go back to the start of you mental book, and make subtle changes to your approaches. I'm not saying "make him wait", because that doesn't always work. I'm saying perhaps enjoy a few dates before sex maybe. Perhaps allow the guy to just go home after a date, and don't even bring it up.
An easy way to do this is to have dates where, afterwards, you have plans with girlfriends. So he simply can't hang around even if you both wanted to have a bit of fun ;)