I already know
Japanese- Aishi teru
Spanish- Te amo
Russian- Ya lublu tibya
But, I want to know many many more ways. Before anybody asks, I don’t want to use Google translate or a similar service. They just don’t work that well.
Hindi: “Maiṁ tumasē pyāra karatā hūm̐,” or “मैं तुमसे प्यार करता हूँ.”
Alright, I admit I got that from Google Translate but that’s only for the spelling of it (as I can only speak and understand Hindi, not read or write it ).
Ich liebe dich: German
Eu te amo: Portuguese
Je t’aime: French
In Dutch: Ik hou(d) van je/jou. - Yeah, weird language, Dutch. Just pick whichever you want to use, it doesn’t matter or change the meaning much. Pronounced “Ick how fon yeh”.
There is a really nice Dutch word related to the subject of love: “lief”. It’s pronounced “leaf” and is the equivalent of the German “lieb”. It means something like nice, or sweet, but… different. It’s a nicer word. You can say “that’s lief of you”, or “you are so lief” or “he is a lief guy”. If you’re feeling dramatic you can say “Ik heb je lief” for “I love you”. You can call your sweetheart “liefie”. It’s a great word and the sound is just right for the meaning. 
In Romanian: Te iubesc.
Fulfulde (spoken across West Africa): Mi yiddi ma
Fulfulde gets a lot of mileage out of words, so “yiddi” encompasses “like,” “love,” “want,” and “need.”
Swedish: Jag älskar dig. Pronounced “ya EL-skar dey.”
Irish (Gaelic): Is grá liom thú. Pron. “Iss graw lum who”
Done. 
Arabic: ana bahebak (I think the ‘ana’ (I) may not be necessary)
愛している would normally be written in the Latin alphabet as one word “Aishiteru”. It has two parts: 愛 (ai), being the noun for “love”, and している (shiteru), being a form of the verb “suru”, which means “to do”. It doesn’t make sense to split “shiteru” between two words.
(And the subject translated as “I” and the object translated as “you” are left out – Japanese often leaves out words that can be understood from the context.)
That was my error. A friend told me how to say I love you in Japanese face to face. I got the pronunciation right but forgot to ask about the transliteration.
To everybody- Thank you very much!
In my experience (which is somewhat limited, admittedly), 好き（だ）suki (da), is more common anyway.
ETA: My Japanese tutor agrees, aishteru is somewhat uncommon, suki is usually used. At least in his dialect (Tokyo).
The weird thing is not that 1) you can omit the final -d in houd, which is often not pronounced, or 2) that there’s stressed and unstressed forms of personal pronouns, or even 3) that such differences are encoded in the spelling. The weirdest thing about Dutch here is that there’s no non-compound verb similar to ‘to love’. What we say is a phrasal verb, something like “I hold of you”. The same is true for ‘to like’ - when we like something on facebook, we ‘find it nice/fun’ (ik vind het leuk) - but the verb ‘to like’ has no direct equivalent in Dutch.
For the thread: Czech - miluju tě.
Malay: saya cinta kamu (romantic love) or saya sayang kamu (affectionate love, as a mother to her child)
For Thai, RickG’s link shows
ผมรักคุณ (phom rak khun) - man talking
ฉันรักคุณ (chan rak khun) - woman talking
An English-speaking layman unfamiliar with phonetic transcription might get a closer pronunciation with the transliterations
pom ruk koon
chun ruk koon
Substitute เธอ (tur) for koon to suggest affection or intimacy.
He also says that 守りたい (mamoritai) – literally “I want to protect you” – is often used to mean “I love you” from a boy to a girl.
Most of the ones I know have already been mentioned…
One left, Slovenian: Ljubim te.
Finnish–rakastan sinua (RAH kah stahn SEE noo ah)
In theory Indonesian and Malaysian should be about the same, but I’m always surprised at the different word choices - I can’t imagine anyone Indonesian using “saya” in the case of romantic love. Anyway, there is more than one way to say it in Indonesian but a common one (as evidenced by its frequent use in Indonesian pop songs) is:
aku mencintaimu