hmm its tricky... countless people have thought theyre in love and realise afterwards that they weren't. there's a fine line between infatuation and being in love/loving someone.
i think especially in the early stages in a relationship it's hard to tell, if it's all passionate and amazing, i think it's only as things go on and you start to perhaps see their flaws that you know for sure... if you know that your boyf can sometimes be a a bit *insert flaw here* but that more often than not you can still stare at him dreamily ffrom across the room its probably genuine lurrve.
i dont know if trust is a mark of love... i love my boyfriend but i dont know yet if i can entirely trust him, but thats just because i have difficulties and feel vulnerable putting myself on the line. i think love is a gut feeling, and that when youre at your most rational and not feeling all romantic and loved up, and you still think, wow, this guy is amazing, then i think it's love.