Should I stay or Should I just go....

TL;DR GF of a 1 year & 8 months started out as a great sex buddy but now things are as arid as a desert and we are only in our 20's. I love her but should I stay or go?

Ok first and foremost forgive me but this is my first post on reddit and I have seen some positive comments people give in relation to posts so I thought I might get a clear perspective from you guys. Ok so I'm a male (26) and my gf is (23) we've known each other having gone to universities in the same city. Things started off as casual but we gradually became serious and started dating.

To start with sex was great I didn't have to ask or even initiate, she would do so willingly and vigorously and I would also do it willingly and with vigor. I would make sure I paid attention to her needs and she would also pay attention to mine. I know sex isn't everything and she is a very caring, humble, sweet & considerate person and I would actually probably see myself with her for the rest of my life we are very eccentric, creative and we get along together all except for the fact that sex has generally grinded to a halt!

Now I have to ask, make arrangements as to when we can have sex and even doing that it feels forced and I feel very uneasy about it sometimes I don't even ask. Before we dated we could have sex 5 or 6 times in one night now it's once a month or twice if I'm lucky.

I am a loving person I don't cheat on her I take care of myself I hit the gym four times a week I make sure I make the effort with duties around the flat or listening and even giving advice or help when she needs it but the 'perfect' girlfriend just doesn't seem to satisfy me sexually and she seems to have a low libido

Now what should I do? Should I stay and hopefully work things out? Maybe suggest therapy? or Should I leave? I get alot of advances from other women so I know its no that she isn't attracted to me so what can it be? I don't know I am just at my wits end because I care about her but she isn't doing it for me in the bedroom anymore, help.